{"id":"CVE-2026-97974","summary":"ipv6: null-check fib6_node before accessing in __ip6_del_rt_siblings()","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: null-check fib6_node before accessing in __ip6_del_rt_siblings()\n\nsyzbot reported a null-ptr-deref in __ip6_del_rt_siblings() [0].\n\nThe stack trace hinted towards a null dereference of rt-\u003efib6_node when\nfn-\u003eleaf is accessed in __ip6_del_rt_siblings(). With\nRTNL_FLAG_DOIT_UNLOCKED set, inet6_rtm_delroute() operations run\nconcurrently without acquiring the RTNL lock. In ip6_route_del(), the\nroute lookup happens under rcu_read_lock() without acquiring\ntable-\u003etb6_lock.\n\nBetween ip6_route_del() looking up the route and __ip6_del_rt_siblings()\nacquiring table-\u003etb6_lock, another thread can modify the routing table.\nFor example, when an ECMP route is replaced via RTM_NEWROUTE with\nNLM_F_REPLACE, fib6_add_rt2node() unlinks all old siblings and sets\niter-\u003efib6_node = NULL. A reproducer was found that triggers this [1].\n\nAdd a check to ensure rt-\u003efib6_node is non-null before accessing it.\n\n[0]\nKASAN: null-ptr-deref in range [0x0000000000000020-0x0000000000000027]\nRIP: 0010:__ip6_del_rt_siblings+0x31e/0x7c0 net/ipv6/route.c:4056\nCall Trace:\n \u003cTASK\u003e\n ip6_route_del+0x1054/0x1110 net/ipv6/route.c:4232\n inet6_rtm_delroute+0x5d7/0x6d0 net/ipv6/route.c:5669\n rtnetlink_rcv_msg+0x802/0xc00 net/core/rtnetlink.c:7132\n netlink_rcv_skb+0x226/0x4a0 net/netlink/af_netlink.c:2556\n netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]\n netlink_unicast+0x7f5/0x990 net/netlink/af_netlink.c:1345\n netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1900\n sock_sendmsg_nosec+0x13a/0x180 net/socket.c:800\n __sock_sendmsg net/socket.c:815 [inline]\n ____sys_sendmsg+0x565/0x870 net/socket.c:2713\n ___sys_sendmsg+0x2a5/0x360 net/socket.c:2767\n __sys_sendmsg net/socket.c:2799 [inline]\n __do_sys_sendmsg net/socket.c:2804 [inline]\n __se_sys_sendmsg net/socket.c:2802 [inline]\n __x64_sys_sendmsg+0x1b7/0x290 net/socket.c:2802\n do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]\n do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84\n entry_SYSCALL_64_after_hwframe+0x77/0x7f\n \u003c/TASK\u003e\n\n[1] https://gist.github.com/NamanGulati/0766a1159b6ca61928faaf87425ff899","modified":"2026-09-26T03:48:27.926759956Z","published":"2026-09-25T10:23:13.373Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/97xxx/CVE-2026-97974.json","cna_assigner":"Linux"},"references":[{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"},{"type":"WEB","url":"https://git.kernel.org/stable/c/1155234c2227cf36072a43e1e09119472ade7ca7"},{"type":"WEB","url":"https://git.kernel.org/stable/c/cdca92eddc025fdb90071be97738f7d55a65f8dd"},{"type":"WEB","url":"https://git.kernel.org/stable/c/e7ff91f19c1aae039a4257fa86fe849afe185291"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/97xxx/CVE-2026-97974.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-97974"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"bd11ff421d36abdb585b9104fa70057bf01b3110"},{"fixed":"e7ff91f19c1aae039a4257fa86fe849afe185291"},{"fixed":"1155234c2227cf36072a43e1e09119472ade7ca7"},{"fixed":"cdca92eddc025fdb90071be97738f7d55a65f8dd"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-97974.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.16.0"},{"fixed":"6.18.53"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.2.7"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-97974.json"}}],"schema_version":"1.9.0"}