{"id":"CVE-2026-74562","summary":"nexthop: take nh-\u003elock for f6i_list walks in replace check and notify","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nnexthop: take nh-\u003elock for f6i_list walks in replace check and notify\n\nfib6_check_nh_list() and __nexthop_replace_notify() walk nh-\u003ef6i_list\nduring an RTNL-serialized nexthop replace without holding nh-\u003elock. IPv6\nRTM_NEWROUTE/RTM_DELROUTE run without RTNL and mutate that list under\nnh-\u003elock (fib6_add_rt2node_nh(), fib6_purge_rt()), so both walks race a\nconcurrent route delete that unlinks and frees a fib6_info:\n\n  BUG: KASAN: slab-use-after-free in rt6_fill_node.isra.0 (net/ipv6/route.c:5799)\n  Read of size 4 at addr ffff888014607e64 by task exploit/143\n   rt6_fill_node.isra.0 (net/ipv6/route.c:5799)\n   fib6_rt_update (net/ipv6/route.c:6412)\n   __nexthop_replace_notify (net/ipv4/nexthop.c:2542)\n   rtm_new_nexthop (net/ipv4/nexthop.c:2554)\n   rtnetlink_rcv_msg (net/core/rtnetlink.c:7076)\n\n  BUG: KASAN: slab-use-after-free in fib6_check_nh_list (net/ipv4/nexthop.c:1605)\n  Read of size 8 at addr ffff888014a7d068 by task exploit/142\n   fib6_check_nh_list (net/ipv4/nexthop.c:1605)\n   rtm_new_nexthop (net/ipv4/nexthop.c:2575)\n   rtnetlink_rcv_msg (net/core/rtnetlink.c:7076)\n\nBoth walks only read the entries and take no tb6_lock, so protect them\nwith nh-\u003elock; fib6_rt_update() uses gfp_any(), which returns GFP_ATOMIC\nunder the lock.","modified":"2026-08-18T03:56:51.349887975Z","published":"2026-08-15T12:28:05.154Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74562.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/072cd1f21819dedd2252e704d255de3b0cfc61a7"},{"type":"WEB","url":"https://git.kernel.org/stable/c/bb2b072c619c1f741a6234257050f72005dc63ef"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74562.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-74562"},{"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":"081efd18326e353c6fbfdeff903a83edde953f72"},{"fixed":"bb2b072c619c1f741a6234257050f72005dc63ef"},{"fixed":"072cd1f21819dedd2252e704d255de3b0cfc61a7"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-74562.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.16.0"},{"fixed":"7.1.8"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-74562.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H"}]}