CVE-2026-63816

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-63816", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-07-19T07:54:57.014Z", "datePublished": "2026-07-19T12:02:15.907Z", "dateUpdated": "2026-08-17T04:51:23.480Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-17T04:51:23.480Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nf2fs: atomic: fix UAF issue on f2fs_inode_info.atomic_inode\n\n- ioctl(F2FS_IOC_GARBAGE_COLLECT_RANGE)\t\t- shrink\n - f2fs_gc\n - gc_data_segment\n - ra_data_block(cow_inode)\n - mapping = F2FS_I(inode)->atomic_inode->i_mapping\n : f2fs_is_cow_file(cow_inode) is true\n\t\t\t\t\t\t - f2fs_evict_inode(atomic_inode)\n\t\t\t\t\t\t - clear_inode_flag(fi->cow_inode, FI_COW_FILE)\n\t\t\t\t\t\t - F2FS_I(fi->cow_inode)->atomic_inode = NULL\n\t\t\t\t\t\t ...\n\t\t\t\t\t\t - truncate_inode_pages_final(atomic_inode)\n - f2fs_grab_cache_folio(mapping)\n : create folio in atomic_inode->mapping\n\t\t\t\t\t\t - clear_inode(atomic_inode)\n\t\t\t\t\t\t - BUG_ON(atomic_inode->i_data.nrpages)\n\nWe need to add a reference on fi->atomic_inode before using its mapping\nfield during garbage collection, otherwise, it will cause UAF issue."}], "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 - Exploitation requires local access through filesystem syscalls and ioctls (atomic-write ioctls, file I/O, close/evict) on an F2FS mount; there is no network-facing entry point to the vulnerable GC path.\nAC:L - The attacker controls both sides of the race by running concurrent threads that perform atomic writes/commits/closes while filling the filesystem or driving writes to trigger background or foreground GC via f2fs_balance_fs and the f2fs_gc kthread.\nPR:L - No real root is required; an unprivileged local user with write access to their own files on F2FS can use atomic-write ioctls and normal I/O to reach the bug, while GC runs automatically without CAP_SYS_ADMIN.\nUI:N - The attacker can trigger the full exploit chain on files they own without any separate victim user performing actions; atomic-write setup, GC pressure, and inode eviction are all orchestrated by the attacker process.\nS:U - Impact is kernel memory corruption and potential local privilege escalation within the same kernel security boundary, not a cross-VM or cross-container escape to a different security authority.\nC:H - This is a use-after-free on a live inode address_space; the freed atomic_inode can be reused or read through stale mapping pointers, enabling arbitrary kernel memory disclosure primitives.\nI:H - UAF on inode mapping during folio allocation allows heap corruption and control of freed object contents, which is exploitable for arbitrary kernel write and local privilege escalation.\nA:H - The race reliably leads to kernel BUG_ON in clear_inode when nrpages is nonzero, and UAF corruption can cause kernel oops or panic even before full exploitation."}]}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["fs/f2fs/gc.c", "fs/f2fs/inode.c"], "versions": [{"version": "3db1de0e582c358dd013f3703cd55b5fe4076436", "lessThan": "7d3ae21783e5914c1761ac7d63f882d3d70800e9", "status": "affected", "versionType": "git"}, {"version": "3db1de0e582c358dd013f3703cd55b5fe4076436", "lessThan": "56038756aae68312df00d4aa1d97e51ef3aca725", "status": "affected", "versionType": "git"}, {"version": "3db1de0e582c358dd013f3703cd55b5fe4076436", "lessThan": "a499f77c06050a28c897bdbd86cd2f0721ae0743", "status": "affected", "versionType": "git"}, {"version": "3db1de0e582c358dd013f3703cd55b5fe4076436", "lessThan": "a805fec35c201c59643ddcde713bce4051c8ee27", "status": "affected", "versionType": "git"}, {"version": "3db1de0e582c358dd013f3703cd55b5fe4076436", "lessThan": "e0288584baa5dc41df4a829a023c4c1b33fe53d7", "status": "affected", "versionType": "git"}, {"version": "6db52f1944417c2601182a591a704e2f119c5215", "status": "affected", "versionType": "git"}, {"version": "5.18.18", "lessThan": "5.19", "status": "affected", "versionType": "semver"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["fs/f2fs/gc.c", "fs/f2fs/inode.c"], "versions": [{"version": "5.19", "status": "affected"}, {"version": "0", "lessThan": "5.19", "status": "unaffected", "versionType": "semver"}, {"version": "6.6.145", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.96", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.39", "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": "5.19", "versionEndExcluding": "6.6.145"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.19", "versionEndExcluding": "6.12.96"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.19", "versionEndExcluding": "6.18.39"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.19", "versionEndExcluding": "7.1.3"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.19", "versionEndExcluding": "7.2"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.18.18"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/7d3ae21783e5914c1761ac7d63f882d3d70800e9"}, {"url": "https://git.kernel.org/stable/c/56038756aae68312df00d4aa1d97e51ef3aca725"}, {"url": "https://git.kernel.org/stable/c/a499f77c06050a28c897bdbd86cd2f0721ae0743"}, {"url": "https://git.kernel.org/stable/c/a805fec35c201c59643ddcde713bce4051c8ee27"}, {"url": "https://git.kernel.org/stable/c/e0288584baa5dc41df4a829a023c4c1b33fe53d7"}], "title": "f2fs: atomic: fix UAF issue on f2fs_inode_info.atomic_inode", "x_generator": {"engine": "bippy-1.2.0"}}}}

{}

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f2fs_gc\n - gc_data_segment\n - ra_data_block(cow_inode)\n - mapping = F2FS_I(inode)->atomic_inode->i_mapping\n : f2fs_is_cow_file(cow_inode) is true\n\t\t\t\t\t\t - f2fs_evict_inode(atomic_inode)\n\t\t\t\t\t\t - clear_inode_flag(fi->cow_inode, FI_COW_FILE)\n\t\t\t\t\t\t - F2FS_I(fi->cow_inode)->atomic_inode = NULL\n\t\t\t\t\t\t ...\n\t\t\t\t\t\t - truncate_inode_pages_final(atomic_inode)\n - f2fs_grab_cache_folio(mapping)\n : create folio in atomic_inode->mapping\n\t\t\t\t\t\t - clear_inode(atomic_inode)\n\t\t\t\t\t\t - BUG_ON(atomic_inode->i_data.nrpages)\n\nWe need to add a reference on fi->atomic_inode before using its mapping\nfield during garbage collection, otherwise, it will cause UAF issue."}], "id": "CVE-2026-63816", "lastModified": "2026-11-10T20:43:44.910", "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"}]}, "published": "2026-07-19T12:16:54.643", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/56038756aae68312df00d4aa1d97e51ef3aca725"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/7d3ae21783e5914c1761ac7d63f882d3d70800e9"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/a499f77c06050a28c897bdbd86cd2f0721ae0743"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/a805fec35c201c59643ddcde713bce4051c8ee27"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/e0288584baa5dc41df4a829a023c4c1b33fe53d7"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Analyzed", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-416"}], "source": "nvd@nist.gov", "type": "Primary"}]}

{"bugzilla": {"description": "kernel: f2fs: atomic: fix UAF issue on f2fs_inode_info.atomic_inode", "id": "2502263", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2502263"}, "csaw": false, "cwe": "CWE-825", "details": ["In the Linux kernel, the following vulnerability has been resolved:\nf2fs: atomic: fix UAF issue on f2fs_inode_info.atomic_inode\n- ioctl(F2FS_IOC_GARBAGE_COLLECT_RANGE)- shrink\n- f2fs_gc\n- gc_data_segment\n- ra_data_block(cow_inode)\n- mapping = F2FS_I(inode)->atomic_inode->i_mapping\n: f2fs_is_cow_file(cow_inode) is true\n- f2fs_evict_inode(atomic_inode)\n- clear_inode_flag(fi->cow_inode, FI_COW_FILE)\n- F2FS_I(fi->cow_inode)->atomic_inode = NULL\n...\n- truncate_inode_pages_final(atomic_inode)\n- f2fs_grab_cache_folio(mapping)\n: create folio in atomic_inode->mapping\n- clear_inode(atomic_inode)\n- BUG_ON(atomic_inode->i_data.nrpages)\nWe need to add a reference on fi->atomic_inode before using its mapping\nfield during garbage collection, otherwise, it will cause UAF issue.", "A flaw was found in the f2fs (Flash-Friendly File System) component of the Linux kernel. This use-after-free (UAF) vulnerability occurs during garbage collection operations when handling Copy-On-Write (COW) files. A local attacker could exploit this by triggering garbage collection, leading to a premature deallocation of memory. Subsequent access to this freed memory could result in a system crash, causing a Denial of Service (DoS), or potentially lead to privilege escalation."], "name": "CVE-2026-63816", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Fix deferred", "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": "Fix deferred", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Fix deferred", "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-2026-63816\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-63816\nhttps://lore.kernel.org/linux-cve-announce/2026071904-CVE-2026-63816-0e95@gregkh/T"]}

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