CVE-2026-63809

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-63809", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-07-19T07:54:57.013Z", "datePublished": "2026-07-19T12:02:11.905Z", "dateUpdated": "2026-10-19T20:07:48.575Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-17T04:51:15.528Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: use kvfree() for replaced sysctl write buffer\n\nproc_sys_call_handler() allocates its temporary sysctl buffer with\nkvzalloc() and passes it to __cgroup_bpf_run_filter_sysctl(). Since\nkvzalloc() may fall back to vmalloc() for large allocations, freeing\nthat buffer with kfree() is wrong and can corrupt memory.\n\nUse kvfree() to safely handle both kmalloc and kvzalloc()/vmalloc\nallocations.\n\nThe bug was first flagged by an experimental analysis tool we are\ndeveloping for kernel memory-management bugs while analyzing\nv6.13-rc1. The tool is still under development and is not yet publicly\navailable. Manual inspection confirms that the bug is still\npresent in v7.1-rc5.\n\nReproduced the bug based on v7.1-rc4 in a QEMU x86_64 guest booted with\nKASAN and CONFIG_FAILSLAB enabled. To exercise the replacement path, the\ntest tree also included the accompanying fix for the stale ret == 1\ncheck in __cgroup_bpf_run_filter_sysctl(). The reproducer confines\nfailslab injections to the proc_sys_call_handler() range, uses\nstacktrace-depth=32, and injects fail-nth=1 while writing 8191 bytes to\n/proc/sys/kernel/domainname from a task in the target cgroup. Under\nthat setup, fail-nth=1 triggered the fault:\n\n BUG: unable to handle page fault for address: ffffeb0200024d48\n #PF: supervisor read access in kernel mode\n #PF: error_code(0x0000) - not-present page\n PGD 0 P4D 0\n Oops: Oops: 0000 SMP KASAN NOPTI\n CPU: 2 UID: 0 PID: 209 Comm: repro_proc_sys_ Not tainted 7.1.0-rc4-00686-g97625979a5d4 PREEMPT(lazy)\n Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.15.0-1 04/01/2014\n RIP: 0010:kfree+0x6e/0x510\n ...\n Call Trace:\n <TASK>\n ? __cgroup_bpf_run_filter_sysctl+0x626/0xc30\n __cgroup_bpf_run_filter_sysctl+0x74d/0xc30\n ? __pfx___cgroup_bpf_run_filter_sysctl+0x10/0x10\n ? srso_return_thunk+0x5/0x5f\n ? __kvmalloc_node_noprof+0x345/0x870\n ? proc_sys_call_handler+0x250/0x480\n ? srso_return_thunk+0x5/0x5f\n proc_sys_call_handler+0x3a2/0x480\n ? __pfx_proc_sys_call_handler+0x10/0x10\n ? srso_return_thunk+0x5/0x5f\n ? selinux_file_permission+0x39f/0x500\n ? srso_return_thunk+0x5/0x5f\n ? lock_is_held_type+0x9e/0x120\n vfs_write+0x98e/0x1000\n ...\n </TASK>\n\nWith this fix applied on top of the same test setup, rerunning the\nreproducer with fail-nth=1 yields no corresponding Oops reports."}], "metrics": [{"cvssV3_1": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH"}, "scenarios": [{"lang": "en", "value": "AV:L - The bug is reached only via a local write() to /proc/sys/* through proc_sys_call_handler() \u2192 BPF_CGROUP_RUN_PROG_SYSCTL() \u2192 __cgroup_bpf_run_filter_sysctl(); there is no network, adjacent-radio, or physical-device entry point.\nAC:L - An attacker controls all prerequisites: they can mount/join a cgroup, load and attach a cgroup/sysctl BPF program that calls bpf_sysctl_set_new_value(), issue a >PAGE_SIZE sysctl write, and induce kmalloc failure (e.g., memory pressure) so kvzalloc() falls back to vmalloc and the wrong kfree() path is taken.\nPR:L - In a user+network namespace (unshare -Urn), CAP_NET_ADMIN grants write access to /proc/sys/net/* sysctls, and CAP_BPF plus CAP_NET_ADMIN suffice to load/attach BPF_PROG_TYPE_CGROUP_SYSCTL; cgroup management is available with namespace CAP_SYS_ADMIN, without init-namespace root.\nUI:N - Exploitation is fully attacker-driven through syscalls (write, bpf) and requires no victim interaction.\nS:U - Impact is kernel memory corruption and potential privilege escalation within the same kernel/host security boundary, not a cross-boundary escape such as VM or IOMMU bypass.\nC:H - Calling kfree() on a vmalloc-backed kvzalloc() buffer corrupts slab allocator metadata and can be leveraged for arbitrary kernel memory disclosure, not merely a bounded leak.\nI:H - Invalid kfree() of vmalloc memory is a heap corruption primitive that can corrupt slab freelists and be developed into arbitrary kernel writes or code execution.\nA:H - The reproducer triggers an immediate kernel oops/page fault in kfree(), and the underlying allocator corruption can also cause panics, hangs, or repeated crashes."}]}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["kernel/bpf/cgroup.c"], "versions": [{"version": "b7925acd82926ebbf94a0f0783a3961f4e558856", "lessThan": "d0a81ed5ff5d0f9c3f63a4f9e5a4642c363ecd3e", "status": "affected", "versionType": "git"}, {"version": "4508943794efdd94171549c0bd52810e2f4ad9fe", "lessThan": "77355ef7a9f6b0d2bdf65be3b37f2c1f365e20d2", "status": "affected", "versionType": "git"}, {"version": "4508943794efdd94171549c0bd52810e2f4ad9fe", "lessThan": "e1d1e203a6000804c5d3b8a4aa4e52303c0c7ab2", "status": "affected", "versionType": "git"}, {"version": "4508943794efdd94171549c0bd52810e2f4ad9fe", "lessThan": "81fc9a13acae99966232f0e055eb2e445263b89a", "status": "affected", "versionType": "git"}, {"version": "4508943794efdd94171549c0bd52810e2f4ad9fe", "lessThan": "838fe9c28121777c59a9406710a68fcf77bb8017", "status": "affected", "versionType": "git"}, {"version": "4508943794efdd94171549c0bd52810e2f4ad9fe", "lessThan": "65bd0c0afb0e1bf3287458e342429b069624f7d4", "status": "affected", "versionType": "git"}, {"version": "4508943794efdd94171549c0bd52810e2f4ad9fe", "lessThan": "70df4de46577fab5e25418f014583155a147c902", "status": "affected", "versionType": "git"}, {"version": "4508943794efdd94171549c0bd52810e2f4ad9fe", "lessThan": "4c21b5927d4364bfe7365f2700da5fea0ed0d004", "status": "affected", "versionType": "git"}, {"version": "66258ab303588936ee1ee0794d9a271be24f73cb", "status": "affected", "versionType": "git"}, {"version": "5.10.20", "lessThan": "5.10.260", "status": "affected", "versionType": "semver"}, {"version": "5.11.3", "lessThan": "5.12", "status": "affected", "versionType": "semver"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["kernel/bpf/cgroup.c"], "versions": [{"version": "5.12", "status": "affected"}, {"version": "0", "lessThan": "5.12", "status": "unaffected", "versionType": "semver"}, {"version": "5.10.260", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver"}, {"version": "5.15.211", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.1.177", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.6.144", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.95", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.38", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.1.3", "lessThanOrEqual": "7.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.2", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix"}]}], "cpeApplicability": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.10.20", "versionEndExcluding": "5.10.260"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.12", "versionEndExcluding": "5.15.211"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.12", "versionEndExcluding": "6.1.177"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.12", "versionEndExcluding": "6.6.144"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.12", "versionEndExcluding": "6.12.95"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.12", "versionEndExcluding": "6.18.38"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.12", "versionEndExcluding": "7.1.3"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.12", "versionEndExcluding": "7.2"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.11.3"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/d0a81ed5ff5d0f9c3f63a4f9e5a4642c363ecd3e"}, {"url": "https://git.kernel.org/stable/c/77355ef7a9f6b0d2bdf65be3b37f2c1f365e20d2"}, {"url": "https://git.kernel.org/stable/c/e1d1e203a6000804c5d3b8a4aa4e52303c0c7ab2"}, {"url": "https://git.kernel.org/stable/c/81fc9a13acae99966232f0e055eb2e445263b89a"}, {"url": "https://git.kernel.org/stable/c/838fe9c28121777c59a9406710a68fcf77bb8017"}, {"url": "https://git.kernel.org/stable/c/65bd0c0afb0e1bf3287458e342429b069624f7d4"}, {"url": "https://git.kernel.org/stable/c/70df4de46577fab5e25418f014583155a147c902"}, {"url": "https://git.kernel.org/stable/c/4c21b5927d4364bfe7365f2700da5fea0ed0d004"}], "title": "bpf: use kvfree() for replaced sysctl write buffer", "x_generator": {"engine": "bippy-1.2.0"}}, "adp": [{"metrics": [{"other": {"type": "ssvc", "content": {"id": "CVE-2026-63809", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "total"}], "version": "2.0.3", "timestamp": "2026-10-16T15:31:06.256343Z"}}}], "problemTypes": [{"descriptions": [{"lang": "en", "type": "CWE", "cweId": "CWE-787", "description": "CWE-787 Out-of-bounds Write"}]}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-10-19T20:07:48.575Z"}}]}}

{"dataType": "CVE_RECORD", "containers": {"adp": [{"title": "CISA ADP Vulnrichment", "metrics": [{"other": {"type": "ssvc", "content": {"id": "CVE-2026-63809", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "total"}], "version": "2.0.3", "timestamp": "2026-10-16T15:31:06.256343Z"}}}], "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-10-16T15:31:07.227Z"}}], "cna": {"title": "bpf: use kvfree() for replaced sysctl write buffer", "metrics": [{"cvssV3_1": {"version": "3.1", "baseScore": 7.8, "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"}, "scenarios": [{"lang": "en", "value": "AV:L - The bug is reached only via a local write() to /proc/sys/* through proc_sys_call_handler() \u2192 BPF_CGROUP_RUN_PROG_SYSCTL() \u2192 __cgroup_bpf_run_filter_sysctl(); there is no network, adjacent-radio, or physical-device entry point.\nAC:L - An attacker controls all prerequisites: they can mount/join a cgroup, load and attach a cgroup/sysctl BPF program that calls bpf_sysctl_set_new_value(), issue a >PAGE_SIZE sysctl write, and induce kmalloc failure (e.g., memory pressure) so kvzalloc() falls back to vmalloc and the wrong kfree() path is taken.\nPR:L - In a user+network namespace (unshare -Urn), CAP_NET_ADMIN grants write access to /proc/sys/net/* sysctls, and CAP_BPF plus CAP_NET_ADMIN suffice to load/attach BPF_PROG_TYPE_CGROUP_SYSCTL; cgroup management is available with namespace CAP_SYS_ADMIN, without init-namespace root.\nUI:N - Exploitation is fully attacker-driven through syscalls (write, bpf) and requires no victim interaction.\nS:U - Impact is kernel memory corruption and potential privilege escalation within the same kernel/host security boundary, not a cross-boundary escape such as VM or IOMMU bypass.\nC:H - Calling kfree() on a vmalloc-backed kvzalloc() buffer corrupts slab allocator metadata and can be leveraged for arbitrary kernel memory disclosure, not merely a bounded leak.\nI:H - Invalid kfree() of vmalloc memory is a heap corruption primitive that can corrupt slab freelists and be developed into arbitrary kernel writes or code execution.\nA:H - The reproducer triggers an immediate kernel oops/page fault in kfree(), and the underlying allocator corruption can also cause panics, hangs, or repeated crashes."}]}], "affected": [{"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "product": "Linux", "versions": [{"status": "affected", "version": "b7925acd82926ebbf94a0f0783a3961f4e558856", "lessThan": "d0a81ed5ff5d0f9c3f63a4f9e5a4642c363ecd3e", "versionType": "git"}, {"status": "affected", "version": "4508943794efdd94171549c0bd52810e2f4ad9fe", "lessThan": "77355ef7a9f6b0d2bdf65be3b37f2c1f365e20d2", "versionType": "git"}, {"status": "affected", "version": "4508943794efdd94171549c0bd52810e2f4ad9fe", "lessThan": "e1d1e203a6000804c5d3b8a4aa4e52303c0c7ab2", "versionType": "git"}, {"status": "affected", "version": "4508943794efdd94171549c0bd52810e2f4ad9fe", "lessThan": "81fc9a13acae99966232f0e055eb2e445263b89a", "versionType": "git"}, {"status": "affected", "version": "4508943794efdd94171549c0bd52810e2f4ad9fe", "lessThan": "838fe9c28121777c59a9406710a68fcf77bb8017", "versionType": "git"}, {"status": "affected", "version": "4508943794efdd94171549c0bd52810e2f4ad9fe", "lessThan": "65bd0c0afb0e1bf3287458e342429b069624f7d4", "versionType": "git"}, {"status": "affected", "version": "4508943794efdd94171549c0bd52810e2f4ad9fe", "lessThan": "70df4de46577fab5e25418f014583155a147c902", "versionType": "git"}, {"status": "affected", "version": "4508943794efdd94171549c0bd52810e2f4ad9fe", "lessThan": "4c21b5927d4364bfe7365f2700da5fea0ed0d004", "versionType": "git"}, {"status": "affected", "version": "66258ab303588936ee1ee0794d9a271be24f73cb", "versionType": "git"}, {"status": "affected", "version": "5.10.20", "lessThan": "5.10.260", "versionType": "semver"}, {"status": "affected", "version": "5.11.3", "lessThan": "5.12", "versionType": "semver"}], "programFiles": ["kernel/bpf/cgroup.c"], "defaultStatus": "unaffected"}, {"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "product": "Linux", "versions": [{"status": "affected", "version": "5.12"}, {"status": "unaffected", "version": "0", "lessThan": "5.12", "versionType": "semver"}, {"status": "unaffected", "version": "5.10.260", "versionType": "semver", "lessThanOrEqual": "5.10.*"}, {"status": "unaffected", "version": "5.15.211", "versionType": "semver", "lessThanOrEqual": "5.15.*"}, {"status": "unaffected", "version": "6.1.177", "versionType": "semver", "lessThanOrEqual": "6.1.*"}, {"status": "unaffected", "version": "6.6.144", "versionType": "semver", "lessThanOrEqual": "6.6.*"}, {"status": "unaffected", "version": "6.12.95", "versionType": "semver", "lessThanOrEqual": "6.12.*"}, {"status": "unaffected", "version": "6.18.38", "versionType": "semver", "lessThanOrEqual": "6.18.*"}, {"status": "unaffected", "version": "7.1.3", "versionType": "semver", "lessThanOrEqual": "7.1.*"}, {"status": "unaffected", "version": "7.2", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*"}], "programFiles": ["kernel/bpf/cgroup.c"], "defaultStatus": "affected"}], "references": [{"url": "https://git.kernel.org/stable/c/d0a81ed5ff5d0f9c3f63a4f9e5a4642c363ecd3e"}, {"url": "https://git.kernel.org/stable/c/77355ef7a9f6b0d2bdf65be3b37f2c1f365e20d2"}, {"url": "https://git.kernel.org/stable/c/e1d1e203a6000804c5d3b8a4aa4e52303c0c7ab2"}, {"url": "https://git.kernel.org/stable/c/81fc9a13acae99966232f0e055eb2e445263b89a"}, {"url": "https://git.kernel.org/stable/c/838fe9c28121777c59a9406710a68fcf77bb8017"}, {"url": "https://git.kernel.org/stable/c/65bd0c0afb0e1bf3287458e342429b069624f7d4"}, {"url": "https://git.kernel.org/stable/c/70df4de46577fab5e25418f014583155a147c902"}, {"url": "https://git.kernel.org/stable/c/4c21b5927d4364bfe7365f2700da5fea0ed0d004"}], "x_generator": {"engine": "bippy-1.2.0"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: use kvfree() for replaced sysctl write buffer\n\nproc_sys_call_handler() allocates its temporary sysctl buffer with\nkvzalloc() and passes it to __cgroup_bpf_run_filter_sysctl(). Since\nkvzalloc() may fall back to vmalloc() for large allocations, freeing\nthat buffer with kfree() is wrong and can corrupt memory.\n\nUse kvfree() to safely handle both kmalloc and kvzalloc()/vmalloc\nallocations.\n\nThe bug was first flagged by an experimental analysis tool we are\ndeveloping for kernel memory-management bugs while analyzing\nv6.13-rc1. The tool is still under development and is not yet publicly\navailable. Manual inspection confirms that the bug is still\npresent in v7.1-rc5.\n\nReproduced the bug based on v7.1-rc4 in a QEMU x86_64 guest booted with\nKASAN and CONFIG_FAILSLAB enabled. To exercise the replacement path, the\ntest tree also included the accompanying fix for the stale ret == 1\ncheck in __cgroup_bpf_run_filter_sysctl(). The reproducer confines\nfailslab injections to the proc_sys_call_handler() range, uses\nstacktrace-depth=32, and injects fail-nth=1 while writing 8191 bytes to\n/proc/sys/kernel/domainname from a task in the target cgroup. Under\nthat setup, fail-nth=1 triggered the fault:\n\n BUG: unable to handle page fault for address: ffffeb0200024d48\n #PF: supervisor read access in kernel mode\n #PF: error_code(0x0000) - not-present page\n PGD 0 P4D 0\n Oops: Oops: 0000 SMP KASAN NOPTI\n CPU: 2 UID: 0 PID: 209 Comm: repro_proc_sys_ Not tainted 7.1.0-rc4-00686-g97625979a5d4 PREEMPT(lazy)\n Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.15.0-1 04/01/2014\n RIP: 0010:kfree+0x6e/0x510\n ...\n Call Trace:\n <TASK>\n ? __cgroup_bpf_run_filter_sysctl+0x626/0xc30\n __cgroup_bpf_run_filter_sysctl+0x74d/0xc30\n ? __pfx___cgroup_bpf_run_filter_sysctl+0x10/0x10\n ? srso_return_thunk+0x5/0x5f\n ? __kvmalloc_node_noprof+0x345/0x870\n ? proc_sys_call_handler+0x250/0x480\n ? srso_return_thunk+0x5/0x5f\n proc_sys_call_handler+0x3a2/0x480\n ? __pfx_proc_sys_call_handler+0x10/0x10\n ? srso_return_thunk+0x5/0x5f\n ? selinux_file_permission+0x39f/0x500\n ? srso_return_thunk+0x5/0x5f\n ? lock_is_held_type+0x9e/0x120\n vfs_write+0x98e/0x1000\n ...\n </TASK>\n\nWith this fix applied on top of the same test setup, rerunning the\nreproducer with fail-nth=1 yields no corresponding Oops reports."}], "cpeApplicability": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "5.10.260", "versionStartIncluding": "5.10.20"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "5.15.211", "versionStartIncluding": "5.12"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.1.177", "versionStartIncluding": "5.12"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.6.144", "versionStartIncluding": "5.12"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.12.95", "versionStartIncluding": "5.12"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.18.38", "versionStartIncluding": "5.12"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "7.1.3", "versionStartIncluding": "5.12"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "7.2", "versionStartIncluding": "5.12"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionStartIncluding": "5.11.3"}], "operator": "OR"}]}], "providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-17T04:51:15.528Z"}}}, "cveMetadata": {"cveId": "CVE-2026-63809", "state": "PUBLISHED", "dateUpdated": "2026-10-19T20:07:48.575Z", "dateReserved": "2026-07-19T07:54:57.013Z", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "datePublished": "2026-07-19T12:02:11.905Z", "assignerShortName": "Linux"}, "dataVersion": "5.2"}

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Since\nkvzalloc() may fall back to vmalloc() for large allocations, freeing\nthat buffer with kfree() is wrong and can corrupt memory.\n\nUse kvfree() to safely handle both kmalloc and kvzalloc()/vmalloc\nallocations.\n\nThe bug was first flagged by an experimental analysis tool we are\ndeveloping for kernel memory-management bugs while analyzing\nv6.13-rc1. The tool is still under development and is not yet publicly\navailable. Manual inspection confirms that the bug is still\npresent in v7.1-rc5.\n\nReproduced the bug based on v7.1-rc4 in a QEMU x86_64 guest booted with\nKASAN and CONFIG_FAILSLAB enabled. To exercise the replacement path, the\ntest tree also included the accompanying fix for the stale ret == 1\ncheck in __cgroup_bpf_run_filter_sysctl(). The reproducer confines\nfailslab injections to the proc_sys_call_handler() range, uses\nstacktrace-depth=32, and injects fail-nth=1 while writing 8191 bytes to\n/proc/sys/kernel/domainname from a task in the target cgroup. Under\nthat setup, fail-nth=1 triggered the fault:\n\n BUG: unable to handle page fault for address: ffffeb0200024d48\n #PF: supervisor read access in kernel mode\n #PF: error_code(0x0000) - not-present page\n PGD 0 P4D 0\n Oops: Oops: 0000 SMP KASAN NOPTI\n CPU: 2 UID: 0 PID: 209 Comm: repro_proc_sys_ Not tainted 7.1.0-rc4-00686-g97625979a5d4 PREEMPT(lazy)\n Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.15.0-1 04/01/2014\n RIP: 0010:kfree+0x6e/0x510\n ...\n Call Trace:\n <TASK>\n ? __cgroup_bpf_run_filter_sysctl+0x626/0xc30\n __cgroup_bpf_run_filter_sysctl+0x74d/0xc30\n ? __pfx___cgroup_bpf_run_filter_sysctl+0x10/0x10\n ? srso_return_thunk+0x5/0x5f\n ? __kvmalloc_node_noprof+0x345/0x870\n ? proc_sys_call_handler+0x250/0x480\n ? srso_return_thunk+0x5/0x5f\n proc_sys_call_handler+0x3a2/0x480\n ? __pfx_proc_sys_call_handler+0x10/0x10\n ? srso_return_thunk+0x5/0x5f\n ? selinux_file_permission+0x39f/0x500\n ? srso_return_thunk+0x5/0x5f\n ? lock_is_held_type+0x9e/0x120\n vfs_write+0x98e/0x1000\n ...\n </TASK>\n\nWith this fix applied on top of the same test setup, rerunning the\nreproducer with fail-nth=1 yields no corresponding Oops reports."}], "id": "CVE-2026-63809", "lastModified": "2026-10-22T18:46:57.237", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "baseScore": 7.8, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 1.8, "impactScore": 5.9, "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-63809", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "total"}], "role": "CISA Coordinator", "timestamp": "2026-10-16T15:31:06.256343Z", "version": "2.0.3"}}]}, "published": "2026-07-19T12:16:53.757", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/4c21b5927d4364bfe7365f2700da5fea0ed0d004"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/65bd0c0afb0e1bf3287458e342429b069624f7d4"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/70df4de46577fab5e25418f014583155a147c902"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/77355ef7a9f6b0d2bdf65be3b37f2c1f365e20d2"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/81fc9a13acae99966232f0e055eb2e445263b89a"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/838fe9c28121777c59a9406710a68fcf77bb8017"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/d0a81ed5ff5d0f9c3f63a4f9e5a4642c363ecd3e"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/e1d1e203a6000804c5d3b8a4aa4e52303c0c7ab2"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Analyzed", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-763"}], "source": "nvd@nist.gov", "type": "Primary"}, {"description": [{"lang": "en", "value": "CWE-787"}], "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary"}]}

{"bugzilla": {"description": "kernel: bpf: use kvfree() for replaced sysctl write buffer", "id": "2502202", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2502202"}, "csaw": false, "cvss3": {"cvss3_base_score": "7.0", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H", "status": "draft"}, "cwe": "CWE-763", "details": ["In the Linux kernel, the following vulnerability has been resolved:\nbpf: use kvfree() for replaced sysctl write buffer\nproc_sys_call_handler() allocates its temporary sysctl buffer with\nkvzalloc() and passes it to __cgroup_bpf_run_filter_sysctl(). Since\nkvzalloc() may fall back to vmalloc() for large allocations, freeing\nthat buffer with kfree() is wrong and can corrupt memory.\nUse kvfree() to safely handle both kmalloc and kvzalloc()/vmalloc\nallocations.\nThe bug was first flagged by an experimental analysis tool we are\ndeveloping for kernel memory-management bugs while analyzing\nv6.13-rc1. The tool is still under development and is not yet publicly\navailable. Manual inspection confirms that the bug is still\npresent in v7.1-rc5.\nReproduced the bug based on v7.1-rc4 in a QEMU x86_64 guest booted with\nKASAN and CONFIG_FAILSLAB enabled. To exercise the replacement path, the\ntest tree also included the accompanying fix for the stale ret == 1\ncheck in __cgroup_bpf_run_filter_sysctl(). The reproducer confines\nfailslab injections to the proc_sys_call_handler() range, uses\nstacktrace-depth=32, and injects fail-nth=1 while writing 8191 bytes to\n/proc/sys/kernel/domainname from a task in the target cgroup. Under\nthat setup, fail-nth=1 triggered the fault:\nBUG: unable to handle page fault for address: ffffeb0200024d48\n#PF: supervisor read access in kernel mode\n#PF: error_code(0x0000) - not-present page\nPGD 0 P4D 0\nOops: Oops: 0000 SMP KASAN NOPTI\nCPU: 2 UID: 0 PID: 209 Comm: repro_proc_sys_ Not tainted 7.1.0-rc4-00686-g97625979a5d4 PREEMPT(lazy)\nHardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.15.0-1 04/01/2014\nRIP: 0010:kfree+0x6e/0x510\n...\nCall Trace:\n<TASK>\n? __cgroup_bpf_run_filter_sysctl+0x626/0xc30\n__cgroup_bpf_run_filter_sysctl+0x74d/0xc30\n? __pfx___cgroup_bpf_run_filter_sysctl+0x10/0x10\n? srso_return_thunk+0x5/0x5f\n? __kvmalloc_node_noprof+0x345/0x870\n? proc_sys_call_handler+0x250/0x480\n? srso_return_thunk+0x5/0x5f\nproc_sys_call_handler+0x3a2/0x480\n? __pfx_proc_sys_call_handler+0x10/0x10\n? srso_return_thunk+0x5/0x5f\n? selinux_file_permission+0x39f/0x500\n? srso_return_thunk+0x5/0x5f\n? lock_is_held_type+0x9e/0x120\nvfs_write+0x98e/0x1000\n...\n</TASK>\nWith this fix applied on top of the same test setup, rerunning the\nreproducer with fail-nth=1 yields no corresponding Oops reports.", "A flaw was found in the Linux kernel. An issue in the BPF (Berkeley Packet Filter) subsystem's `sysctl` handling can lead to memory corruption. Specifically, when a temporary buffer is allocated using `kvzalloc()` but incorrectly freed with `kfree()`, it can corrupt memory. A local attacker could exploit this vulnerability to cause a system crash, leading to a denial of service."], "name": "CVE-2026-63809", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2026-07-19T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-63809\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-63809\nhttps://lore.kernel.org/linux-cve-announce/2026071903-CVE-2026-63809-0af7@gregkh/T"], "threat_severity": "Moderate"}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[b7925acd82926ebbf94a0f0783a3961f4e558856,d0a81ed5ff5d0f9c3f63a4f9e5a4642c363ecd3e)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[4508943794efdd94171549c0bd52810e2f4ad9fe,77355ef7a9f6b0d2bdf65be3b37f2c1f365e20d2)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[4508943794efdd94171549c0bd52810e2f4ad9fe,e1d1e203a6000804c5d3b8a4aa4e52303c0c7ab2)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[4508943794efdd94171549c0bd52810e2f4ad9fe,81fc9a13acae99966232f0e055eb2e445263b89a)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[4508943794efdd94171549c0bd52810e2f4ad9fe,838fe9c28121777c59a9406710a68fcf77bb8017)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[4508943794efdd94171549c0bd52810e2f4ad9fe,65bd0c0afb0e1bf3287458e342429b069624f7d4)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[4508943794efdd94171549c0bd52810e2f4ad9fe,70df4de46577fab5e25418f014583155a147c902)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[4508943794efdd94171549c0bd52810e2f4ad9fe,4c21b5927d4364bfe7365f2700da5fea0ed0d004)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "66258ab303588936ee1ee0794d9a271be24f73cb"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[5.10.20,5.10.260)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[5.11.3,5.12)"}}], "enrichment": {"confidence": 99.0, "confidence_source": "inferred", "scores": [{"score": 99.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}, {"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "5.12"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[0,5.12)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[0,5.10.*]"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[0,5.15.*]"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[0,6.1.*]"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[0,6.6.*]"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[0,6.12.*]"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[0,6.18.*]"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[0,7.1.*]"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[7.2-rc1,*]"}}], "enrichment": {"confidence": 99.0, "confidence_source": "inferred", "scores": [{"score": 99.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}], "created": "2026-07-21T02:15:04.202673+00:00", "updated": "2026-10-20T14:15:14.438378+00:00", "vendors": ["linux", "linux$PRODUCT$linux_kernel"]}