{"id":"CVE-2026-74561","aliases":[],"url":"https://o3.security/vulnerability/CVE-2026-74561","summary":"nexthop: avoid unlocked f6i_list walk in nh_rt_cache_flush","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nnexthop: avoid unlocked f6i_list walk in nh_rt_cache_flush\n\nnh_rt_cache_flush() walks nh->f6i_list during an RTNL-serialized nexthop\nreplace without holding nh->lock, racing the unlocked IPv6 route\nadd/delete that mutate the list under nh->lock and free fib6_info\nentries (nh_rt_cache_flush() is inlined into rtm_new_nexthop()):\n\n  BUG: KASAN: slab-use-after-free in nh_rt_cache_flush (net/ipv4/nexthop.c:2243)\n  Read of size 8 at addr ffff888012953e18 by task exploit/146\n   nh_rt_cache_flush (net/ipv4/nexthop.c:2243)\n   replace_nexthop (net/ipv4/nexthop.c:2610)\n   rtm_new_nexthop (net/ipv4/nexthop.c:3323)\n   rtnetlink_rcv_msg (net/core/rtnetlink.c:7076)\n\nUnlike the other f6i_list walks, this one bumps each route's sernum via\nfib6_update_sernum_upto_root(), which needs tb6_lock; taking nh->lock\naround it would invert the established tb6_lock -> nh->lock order and\ndeadlock. As the only purpose is to invalidate cached dsts, bump the\nIPv6 sernum for the whole netns with rt_genid_bump_ipv6() instead,\nmirroring the rt_cache_flush() already done for IPv4 just above.","published":"2026-08-15T12:28:04.525Z","modified":"2026-08-18T03:56:30.682763276Z","cvss":{"score":8.8,"severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H"},"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"Linux","name":"Kernel","fixedVersion":"7.1.8"}],"fix":null,"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/44f53e4331a30fabc38a411fae7524341b618db3"},{"type":"WEB","url":"https://git.kernel.org/stable/c/4787a6d2629b4e8c0b6bacab1f75c1660eca44d9"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74561.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-74561"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-18T03:56:30.682763276Z"}}