{"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":"2026-10-03T11:00:50.492Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-10-03T11:00:50.492Z"},"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-rc3","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-rc3"}]}]}],"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"}}}}