{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-97940", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-25T10:18:58.204Z", "datePublished": "2026-09-25T10:22:52.936Z", "dateUpdated": "2026-10-19T09:11:06.854Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T09:11:06.854Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: fix fib6 walker UAF on seq stop\n\nipv6_route_iter_active() treats a walker in FWS_U at the table root as\nalready unlinked. fib6_del_route() can move a still-linked walker into\nthat same state when the current leaf is the last route at the root,\nso ipv6_route_native_seq_stop() skips fib6_walker_unlink(). The seq\nprivate object can then be freed while it remains on\nnet->ipv6.fib6_walkers. A later route deletion walks the dangling list\nand uses the freed walker.\n\nUse the list head as membership state and reinitialize it when\nunlinking. Keep the existing w->node check so a never-started iterator\nwith a zeroed private object is not treated as linked.\n\nThe same stop helper is used by /proc/net/ipv6_route and by the BPF\nipv6_route iterator. The BPF show path only widens the race." } ], "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 by a local read() of /proc/net/ipv6_route (ipv6_route_native_seq_stop via ipv6_route_seq_ops, or the BPF ipv6_route iterator) racing a local RTM_DELROUTE netlink request that runs fib6_del_route(). No remote protocol supplies data that causes the missed fib6_walker_unlink().\nAC:L - The attacker controls both sides of the race. One thread reads /proc/net/ipv6_route while another repeatedly adds and deletes the last route in the table root (e.g. ::/0), which moves the linked walker to FWS_U at the root so seq_stop skips the unlink. The attempt can be retried freely.\nPR:L - /proc/net/ipv6_route is created with mode 0 (0444, world-readable). Deleting routes needs CAP_NET_ADMIN only over the namespace, which an unprivileged user gets with unshare -Urn, and net->ipv6.fib6_walkers is per-namespace, so the whole attack runs in an attacker-owned netns.\nUI:N - No victim action is needed. The attacker opens, reads and closes the proc file and issues the route deletions themselves.\nS:U - The use-after-free happens in kernel heap memory and gives kernel-level impact within the same security authority. No VM or hardware isolation boundary is crossed.\nC:H - The freed seq_file private object (struct ipv6_route_iter, holding the fib6_walker) stays on net->ipv6.fib6_walkers. Later FOR_WALKERS loops read w->state, w->leaf and w->node from memory the attacker can reallocate with controlled contents, a UAF usable for kernel memory disclosure.\nI:H - fib6_del_route() and fib6_repair_tree() write w->leaf, w->state and w->node into the freed walker, and list_add/list_del on w->lh write pointers into it. That is a write primitive into a reallocated kernel heap object, usable for corruption and privilege escalation.\nA:H - Any later route deletion or tree repair in that namespace walks the dangling fib6_walkers entry, which causes list corruption or a KASAN/oops crash of the kernel." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/ipv6/ip6_fib.c" ], "versions": [ { "version": "8d2ca1d7b5c3e63b3a8a81ae99015b615c5f2bf7", "lessThan": "9a3f73d62c86271614eda4c43315230896a37018", "status": "affected", "versionType": "git" }, { "version": "8d2ca1d7b5c3e63b3a8a81ae99015b615c5f2bf7", "lessThan": "63407cddabc5992b5ac03af165559f4a1968a032", "status": "affected", "versionType": "git" }, { "version": "8d2ca1d7b5c3e63b3a8a81ae99015b615c5f2bf7", "lessThan": "05b687ee04f816658f4a9cf586f4d2f129157943", "status": "affected", "versionType": "git" }, { "version": "8d2ca1d7b5c3e63b3a8a81ae99015b615c5f2bf7", "lessThan": "14fdaba201fdff92a3e45994e02bccda409cb19d", "status": "affected", "versionType": "git" }, { "version": "8d2ca1d7b5c3e63b3a8a81ae99015b615c5f2bf7", "lessThan": "0eede1689610e9eeaf729ba86fd1321799eb91a0", "status": "affected", "versionType": "git" }, { "version": "8d2ca1d7b5c3e63b3a8a81ae99015b615c5f2bf7", "lessThan": "b89b691dd00bf39b9ba39ab9446f8c62f419fa7b", "status": "affected", "versionType": "git" }, { "version": "8d2ca1d7b5c3e63b3a8a81ae99015b615c5f2bf7", "lessThan": "4553cfafa8d05c4ce20b1d18f79d9bb3b303fc02", "status": "affected", "versionType": "git" }, { "version": "8d2ca1d7b5c3e63b3a8a81ae99015b615c5f2bf7", "lessThan": "19b4ed644d68098cc62ab612727f40d30f43476c", "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/ipv6/ip6_fib.c" ], "versions": [ { "version": "3.13", "status": "affected" }, { "version": "0", "lessThan": "3.13", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.271", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.222", "lessThanOrEqual": "5.15.*", "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": "6.12.111", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.53", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2.7", "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": "3.13", "versionEndExcluding": "5.10.271" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.13", "versionEndExcluding": "5.15.222" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.13", "versionEndExcluding": "6.1.189" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.13", "versionEndExcluding": "6.6.158" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.13", "versionEndExcluding": "6.12.111" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.13", "versionEndExcluding": "6.18.53" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.13", "versionEndExcluding": "7.2.7" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.13", "versionEndExcluding": "7.3" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/9a3f73d62c86271614eda4c43315230896a37018" }, { "url": "https://git.kernel.org/stable/c/63407cddabc5992b5ac03af165559f4a1968a032" }, { "url": "https://git.kernel.org/stable/c/05b687ee04f816658f4a9cf586f4d2f129157943" }, { "url": "https://git.kernel.org/stable/c/14fdaba201fdff92a3e45994e02bccda409cb19d" }, { "url": "https://git.kernel.org/stable/c/0eede1689610e9eeaf729ba86fd1321799eb91a0" }, { "url": "https://git.kernel.org/stable/c/b89b691dd00bf39b9ba39ab9446f8c62f419fa7b" }, { "url": "https://git.kernel.org/stable/c/4553cfafa8d05c4ce20b1d18f79d9bb3b303fc02" }, { "url": "https://git.kernel.org/stable/c/19b4ed644d68098cc62ab612727f40d30f43476c" } ], "title": "ipv6: fix fib6 walker UAF on seq stop", "x_generator": { "engine": "bippy-1.2.0" } } } }