{"id":"CVE-2026-64538","summary":"ipv6: Fix null-ptr-deref in fib6_nh_mtu_change().","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: Fix null-ptr-deref in fib6_nh_mtu_change().\n\nfib6_nh_mtu_change() re-fetches idev via __in6_dev_get(arg-\u003edev) and\ndereferences idev-\u003ecnf.mtu6 without a NULL check. addrconf_ifdown()\nclears dev-\u003eip6_ptr with RCU_INIT_POINTER() after rt6_disable_ip() has\nreleased tb6_lock, so the RA-driven MTU walk can observe a NULL idev and\noops. The caller rt6_mtu_change_route() guards its own __in6_dev_get(),\nbut this re-fetch is unguarded; nexthop-backed routes survive\naddrconf_ifdown()'s flush, so the walk still reaches it after ip6_ptr is\nnulled.\n\nReturn 0 when idev is NULL, matching rt6_mtu_change_route() and the\nfib6_mtu() fix in commit 5ad509c1fdad (\"ipv6: Fix null-ptr-deref in\nfib6_mtu().\").\n\n  Oops: general protection fault, ... KASAN: null-ptr-deref in range\n        [0x00000000000002a8-0x00000000000002af]\n  RIP: 0010:fib6_nh_mtu_change+0x203/0x990\n   rt6_mtu_change_route+0x141/0x1d0\n   __fib6_clean_all+0xd0/0x160\n   rt6_mtu_change+0xb4/0x100\n   ndisc_router_discovery+0x24b5/0x2cb0\n   icmpv6_rcv+0x12e9/0x1710\n   ipv6_rcv+0x39b/0x410","modified":"2026-08-18T03:31:13.009216951Z","published":"2026-07-27T20:10:32.779Z","related":["openSUSE-SU-2026:11476-1"],"database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64538.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/1451deca9896957159f0666520a792c1b861af4f"},{"type":"WEB","url":"https://git.kernel.org/stable/c/302d57ed7872838b40e56a868fb4c7da7da606e9"},{"type":"WEB","url":"https://git.kernel.org/stable/c/46c3b8191aad3d032776bf3bebf03efdf5f4b905"},{"type":"WEB","url":"https://git.kernel.org/stable/c/6428634f7a0b7878144b4925c37856bef3224967"},{"type":"WEB","url":"https://git.kernel.org/stable/c/80600b5d0f3ecb9324120dc95b5e915130f516c5"},{"type":"WEB","url":"https://git.kernel.org/stable/c/b0d0eb13a0441a8ebf4f227843deaf494f1e2c33"},{"type":"WEB","url":"https://git.kernel.org/stable/c/b2c70dd3326809429b709a9c7e9220d29923051a"},{"type":"WEB","url":"https://git.kernel.org/stable/c/d08d019f2f43a6f9a71e81868bbc326b3afaf37b"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64538.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-64538"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"c0b220cf7d80eb8a36ae9f12cae6df4577a6814e"},{"fixed":"d08d019f2f43a6f9a71e81868bbc326b3afaf37b"},{"fixed":"1451deca9896957159f0666520a792c1b861af4f"},{"fixed":"b2c70dd3326809429b709a9c7e9220d29923051a"},{"fixed":"302d57ed7872838b40e56a868fb4c7da7da606e9"},{"fixed":"80600b5d0f3ecb9324120dc95b5e915130f516c5"},{"fixed":"b0d0eb13a0441a8ebf4f227843deaf494f1e2c33"},{"fixed":"6428634f7a0b7878144b4925c37856bef3224967"},{"fixed":"46c3b8191aad3d032776bf3bebf03efdf5f4b905"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-64538.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.3.0"},{"fixed":"5.10.261"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"5.15.212"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.178"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.145"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.97"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.40"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.1.5"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-64538.json"}}],"schema_version":"1.9.0"}