CVE-2026-98368

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-98368", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-25T10:25:14.344Z", "datePublished": "2026-10-06T08:46:53.292Z", "dateUpdated": "2026-10-19T09:18:20.253Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T09:18:20.253Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nesp: downgrade zerocopy managed frags before mutating skb frags\n\nOn the out-of-place output path (esp->inplace == false) ESP rewrites the\nskb frag array: esp_output_head() appends a trailer frag and\nesp_output_tail() replaces the frags with a destination page, both\nreferenced with get_page().\n\nWhen the skb carries zerocopy managed frags (SKBFL_MANAGED_FRAG_REFS) the\npayload frags are owned by the ubuf and must not be referenced or\nunreferenced individually, but ESP mutates the frag array without ever\ndowngrading the skb. This breaks the managed-frag invariant two ways:\n\n - esp_ssg_unref() walks the source scatterlist and drops a page\n reference for every frag, including the ubuf-owned payload frags,\n pushing their refcount below the GUP pin bias while the pages are\n still pinned, i.e. a use-after-free of the zerocopy pages;\n\n - esp_output_tail() installs its destination page as frag 0 with\n get_page() but leaves SKBFL_MANAGED_FRAG_REFS set, so\n skb_release_data() takes the skip_unref branch and never drops that\n reference, leaking the x->xfrag page at packet rate.\n\nFix this the way every other frag-mutating site does (__ip_append_data(),\n__ip6_append_data(), tcp_sendmsg_locked()) and call\nskb_zcopy_downgrade_managed() before ESP touches the frag array: it takes\na real reference on each existing frag and clears SKBFL_MANAGED_FRAG_REFS,\nso the per-frag unref in esp_ssg_unref() and the frag release in\nskb_release_data() are both balanced and no mixed-ownership frag array is\nleft behind."}], "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 - Managed frags are set only by io_uring's io_sg_from_iter() for IORING_OP_SEND_ZC/SENDMSG_ZC with IORING_RECVSEND_FIXED_BUF, so a local process must submit the zerocopy send that esp_output_head()/esp6_output_head() then mutates; a remote peer cannot produce a SKBFL_MANAGED_FRAG_REFS skb.\nAC:L - The attacker picks every input: an uncloned UDP skb whose data_len+tailen fits in a page and lacks tailroom reliably takes the esp->inplace=false branch, then esp_ssg_unref() drops refs on the ubuf-owned frags. No race or outside state is needed.\nPR:L - io_uring zerocopy send needs no privilege. The ESP SA/policy can be added inside an unprivileged user+net namespace because xfrm_user_rcv_msg only checks netlink_net_capable(CAP_NET_ADMIN); on a host with IPsec already set up, any local user's traffic hits it.\nUI:N - The attacker does everything with their own io_uring ring, registered buffer, socket and (namespaced) xfrm state; no other user has to act.\nS:U - The page refcount underflow and the freed page stay inside the kernel's own authority, so this is a normal local privilege escalation with no VM or sandbox boundary crossed.\nC:H - esp_ssg_unref() pushes the pinned registered-buffer pages' refcount below the GUP pin bias, so the page is freed while io_uring still has it mapped; once reallocated (e.g. as page tables or slab) the attacker can read kernel memory through the stale buffer.\nI:H - Writing through the still-registered fixed buffer into the freed and reallocated page is a page-level use-after-free write primitive (Dirty-Pagetable style), enough for arbitrary kernel memory corruption and privilege escalation.\nA:H - The page UAF leads to bad-page/refcount oopses, and the missing put_page on the x->xfrag page installed by esp_output_tail() leaks memory at packet rate; both can take the system down."}]}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["net/ipv4/esp4.c", "net/ipv6/esp6.c"], "versions": [{"version": "753f1ca4e1e50248a1b760c9774d6d6b354562cc", "lessThan": "2359264f377cdbdef2d95868cc8fb572949e48d3", "status": "affected", "versionType": "git"}, {"version": "753f1ca4e1e50248a1b760c9774d6d6b354562cc", "lessThan": "69a768c12398cada8528080332c822623fa7064d", "status": "affected", "versionType": "git"}, {"version": "753f1ca4e1e50248a1b760c9774d6d6b354562cc", "lessThan": "6508304ac2c8cdafca2f4ab915df8c707893e134", "status": "affected", "versionType": "git"}, {"version": "753f1ca4e1e50248a1b760c9774d6d6b354562cc", "lessThan": "6cab554f2c0f28773f712ed3a5479103f42ce844", "status": "affected", "versionType": "git"}, {"version": "753f1ca4e1e50248a1b760c9774d6d6b354562cc", "lessThan": "0d0845ee61c5df47cc68bc446501f48f71e8dcc6", "status": "affected", "versionType": "git"}, {"version": "753f1ca4e1e50248a1b760c9774d6d6b354562cc", "lessThan": "f89416eb3db151170a6f3c6dfc5239d26cdce4d2", "status": "affected", "versionType": "git"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["net/ipv4/esp4.c", "net/ipv6/esp6.c"], "versions": [{"version": "6.0", "status": "affected"}, {"version": "0", "lessThan": "6.0", "status": "unaffected", "versionType": "semver"}, {"version": "6.1.189", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.6.158", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.112", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.54", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.2.8", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.3", "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": "6.0", "versionEndExcluding": "6.1.189"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.0", "versionEndExcluding": "6.6.158"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.0", "versionEndExcluding": "6.12.112"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.0", "versionEndExcluding": "6.18.54"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.0", "versionEndExcluding": "7.2.8"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.0", "versionEndExcluding": "7.3"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/2359264f377cdbdef2d95868cc8fb572949e48d3"}, {"url": "https://git.kernel.org/stable/c/69a768c12398cada8528080332c822623fa7064d"}, {"url": "https://git.kernel.org/stable/c/6508304ac2c8cdafca2f4ab915df8c707893e134"}, {"url": "https://git.kernel.org/stable/c/6cab554f2c0f28773f712ed3a5479103f42ce844"}, {"url": "https://git.kernel.org/stable/c/0d0845ee61c5df47cc68bc446501f48f71e8dcc6"}, {"url": "https://git.kernel.org/stable/c/f89416eb3db151170a6f3c6dfc5239d26cdce4d2"}], "title": "esp: downgrade zerocopy managed frags before mutating skb frags", "x_generator": {"engine": "bippy-1.2.0"}}}}

{}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["net/ipv4/esp4.c", "net/ipv6/esp6.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "2359264f377cdbdef2d95868cc8fb572949e48d3", "status": "affected", "version": "753f1ca4e1e50248a1b760c9774d6d6b354562cc", "versionType": "git"}, {"lessThan": "69a768c12398cada8528080332c822623fa7064d", "status": "affected", "version": "753f1ca4e1e50248a1b760c9774d6d6b354562cc", "versionType": "git"}, {"lessThan": "6508304ac2c8cdafca2f4ab915df8c707893e134", "status": "affected", "version": "753f1ca4e1e50248a1b760c9774d6d6b354562cc", "versionType": "git"}, {"lessThan": "6cab554f2c0f28773f712ed3a5479103f42ce844", "status": "affected", "version": "753f1ca4e1e50248a1b760c9774d6d6b354562cc", "versionType": "git"}, {"lessThan": "0d0845ee61c5df47cc68bc446501f48f71e8dcc6", "status": "affected", "version": "753f1ca4e1e50248a1b760c9774d6d6b354562cc", "versionType": "git"}, {"lessThan": "f89416eb3db151170a6f3c6dfc5239d26cdce4d2", "status": "affected", "version": "753f1ca4e1e50248a1b760c9774d6d6b354562cc", "versionType": "git"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["net/ipv4/esp4.c", "net/ipv6/esp6.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"status": "affected", "version": "6.0"}, {"lessThan": "6.0", "status": "unaffected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "6.1.*", "status": "unaffected", "version": "6.1.189", "versionType": "semver"}, {"lessThanOrEqual": "6.6.*", "status": "unaffected", "version": "6.6.158", "versionType": "semver"}, {"lessThanOrEqual": "6.12.*", "status": "unaffected", "version": "6.12.112", "versionType": "semver"}, {"lessThanOrEqual": "6.18.*", "status": "unaffected", "version": "6.18.54", "versionType": "semver"}, {"lessThanOrEqual": "7.2.*", "status": "unaffected", "version": "7.2.8", "versionType": "semver"}, {"lessThanOrEqual": "*", "status": "unaffected", "version": "7.3", "versionType": "original_commit_for_fix"}]}], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nesp: downgrade zerocopy managed frags before mutating skb frags\n\nOn the out-of-place output path (esp->inplace == false) ESP rewrites the\nskb frag array: esp_output_head() appends a trailer frag and\nesp_output_tail() replaces the frags with a destination page, both\nreferenced with get_page().\n\nWhen the skb carries zerocopy managed frags (SKBFL_MANAGED_FRAG_REFS) the\npayload frags are owned by the ubuf and must not be referenced or\nunreferenced individually, but ESP mutates the frag array without ever\ndowngrading the skb. This breaks the managed-frag invariant two ways:\n\n - esp_ssg_unref() walks the source scatterlist and drops a page\n reference for every frag, including the ubuf-owned payload frags,\n pushing their refcount below the GUP pin bias while the pages are\n still pinned, i.e. a use-after-free of the zerocopy pages;\n\n - esp_output_tail() installs its destination page as frag 0 with\n get_page() but leaves SKBFL_MANAGED_FRAG_REFS set, so\n skb_release_data() takes the skip_unref branch and never drops that\n reference, leaking the x->xfrag page at packet rate.\n\nFix this the way every other frag-mutating site does (__ip_append_data(),\n__ip6_append_data(), tcp_sendmsg_locked()) and call\nskb_zcopy_downgrade_managed() before ESP touches the frag array: it takes\na real reference on each existing frag and clears SKBFL_MANAGED_FRAG_REFS,\nso the per-frag unref in esp_ssg_unref() and the frag release in\nskb_release_data() are both balanced and no mixed-ownership frag array is\nleft behind."}], "id": "CVE-2026-98368", "lastModified": "2026-10-19T10:18:39.853", "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": "2026-10-06T09:18:31.130", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/0d0845ee61c5df47cc68bc446501f48f71e8dcc6"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/2359264f377cdbdef2d95868cc8fb572949e48d3"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/6508304ac2c8cdafca2f4ab915df8c707893e134"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/69a768c12398cada8528080332c822623fa7064d"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/6cab554f2c0f28773f712ed3a5479103f42ce844"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/f89416eb3db151170a6f3c6dfc5239d26cdce4d2"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Received"}

{"bugzilla": {"description": "kernel: esp: downgrade zerocopy managed frags before mutating skb frags", "id": "2546472", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2546472"}, "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-911", "details": ["In the Linux kernel, the following vulnerability has been resolved:\nesp: downgrade zerocopy managed frags before mutating skb frags\nOn the out-of-place output path (esp->inplace == false) ESP rewrites the\nskb frag array: esp_output_head() appends a trailer frag and\nesp_output_tail() replaces the frags with a destination page, both\nreferenced with get_page().\nWhen the skb carries zerocopy managed frags (SKBFL_MANAGED_FRAG_REFS) the\npayload frags are owned by the ubuf and must not be referenced or\nunreferenced individually, but ESP mutates the frag array without ever\ndowngrading the skb. This breaks the managed-frag invariant two ways:\n- esp_ssg_unref() walks the source scatterlist and drops a page\nreference for every frag, including the ubuf-owned payload frags,\npushing their refcount below the GUP pin bias while the pages are\nstill pinned, i.e. a use-after-free of the zerocopy pages;\n- esp_output_tail() installs its destination page as frag 0 with\nget_page() but leaves SKBFL_MANAGED_FRAG_REFS set, so\nskb_release_data() takes the skip_unref branch and never drops that\nreference, leaking the x->xfrag page at packet rate.\nFix this the way every other frag-mutating site does (__ip_append_data(),\n__ip6_append_data(), tcp_sendmsg_locked()) and call\nskb_zcopy_downgrade_managed() before ESP touches the frag array: it takes\na real reference on each existing frag and clears SKBFL_MANAGED_FRAG_REFS,\nso the per-frag unref in esp_ssg_unref() and the frag release in\nskb_release_data() are both balanced and no mixed-ownership frag array is\nleft behind.", "A flaw was found in the Linux kernel's IPsec Encapsulating Security Payload (ESP) subsystem. When transmitting network packets using zero-copy operations on out-of-place paths, the kernel modifies packet fragment structures without properly updating reference counts for managed memory pages. A local user can exploit this vulnerability by sending network traffic with zero-copy buffers, causing pages to be prematurely released while still in use. This flaw leads to a use-after-free condition that can result in a Denial of Service (DoS) through a kernel crash or potentially allow privilege escalation."], "name": "CVE-2026-98368", "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": "Out of support scope", "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": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/a:redhat:openshift:4", "fix_state": "Not affected", "package_name": "openshift/ose-rhel-coreos-8", "product_name": "Red Hat OpenShift Container Platform 4"}, {"cpe": "cpe:/a:redhat:openshift:4", "fix_state": "Affected", "package_name": "openshift/ose-rhel-coreos-9", "product_name": "Red Hat OpenShift Container Platform 4"}], "public_date": "2026-10-06T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-98368\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-98368\nhttps://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-98368.mbox"], "threat_severity": "Moderate"}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[753f1ca4e1e50248a1b760c9774d6d6b354562cc,2359264f377cdbdef2d95868cc8fb572949e48d3)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[753f1ca4e1e50248a1b760c9774d6d6b354562cc,69a768c12398cada8528080332c822623fa7064d)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[753f1ca4e1e50248a1b760c9774d6d6b354562cc,6508304ac2c8cdafca2f4ab915df8c707893e134)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[753f1ca4e1e50248a1b760c9774d6d6b354562cc,6cab554f2c0f28773f712ed3a5479103f42ce844)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[753f1ca4e1e50248a1b760c9774d6d6b354562cc,0d0845ee61c5df47cc68bc446501f48f71e8dcc6)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[753f1ca4e1e50248a1b760c9774d6d6b354562cc,f89416eb3db151170a6f3c6dfc5239d26cdce4d2)"}}], "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": "generic", "value": "6.0"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[0,6.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.1.189,7.0.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.6.158,6.7.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.12.112,6.13.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.18.54,6.19.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[7.2.8,7.3.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[7.3-rc4,*]"}}], "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": "2026-10-06T14:00:20.948139+00:00", "updated": "2026-10-09T07:00:12.267721+00:00", "vendors": ["linux", "linux$PRODUCT$linux_kernel"]}