{"id":"CVE-2026-74561","title":"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, r…","summary":"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, r…","severity":"high","cvss":8.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H","vendor":"Linux","product":"Linux","affected":["Linux >= 081efd18326e353c6fbfdeff903a83edde953f72 < f97fae992155b11da516a509c855ff9d0868b107","Linux >= 081efd18326e353c6fbfdeff903a83edde953f72 < 44f53e4331a30fabc38a411fae7524341b618db3","Linux >= 081efd18326e353c6fbfdeff903a83edde953f72 < 4787a6d2629b4e8c0b6bacab1f75c1660eca44d9","Linux 6.16"],"published":"2026-08-15","updated":"2026-10-15","sourceUpdated":"2026-10-15T11:17:47.580","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-74561","references":[{"url":"https://git.kernel.org/stable/c/44f53e4331a30fabc38a411fae7524341b618db3","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/4787a6d2629b4e8c0b6bacab1f75c1660eca44d9","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/f97fae992155b11da516a509c855ff9d0868b107","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}],"tags":["nvd","cve.org"],"epss":0.00165,"epssPercentile":0.05325,"ingestedAt":"2026-10-15T11:00:41.671Z","slug":"CVE-2026-74561","body":"## Overview\n\nIn 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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":48,"depthScoreParts":{"impact":48.4,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}