{"id":"CVE-2023-53477","summary":"ipv6: Add lwtunnel encap size of all siblings in nexthop calculation","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: Add lwtunnel encap size of all siblings in nexthop calculation\n\nIn function rt6_nlmsg_size(), the length of nexthop is calculated\nby multipling the nexthop length of fib6_info and the number of\nsiblings. However if the fib6_info has no lwtunnel but the siblings\nhave lwtunnels, the nexthop length is less than it should be, and\nit will trigger a warning in inet6_rt_notify() as follows:\n\nWARNING: CPU: 0 PID: 6082 at net/ipv6/route.c:6180 inet6_rt_notify+0x120/0x130\n......\nCall Trace:\n \u003cTASK\u003e\n fib6_add_rt2node+0x685/0xa30\n fib6_add+0x96/0x1b0\n ip6_route_add+0x50/0xd0\n inet6_rtm_newroute+0x97/0xa0\n rtnetlink_rcv_msg+0x156/0x3d0\n netlink_rcv_skb+0x5a/0x110\n netlink_unicast+0x246/0x350\n netlink_sendmsg+0x250/0x4c0\n sock_sendmsg+0x66/0x70\n ___sys_sendmsg+0x7c/0xd0\n __sys_sendmsg+0x5d/0xb0\n do_syscall_64+0x3f/0x90\n entry_SYSCALL_64_after_hwframe+0x72/0xdc\n\nThis bug can be reproduced by script:\n\nip -6 addr add 2002::2/64 dev ens2\nip -6 route add 100::/64 via 2002::1 dev ens2 metric 100\n\nfor i in 10 20 30 40 50 60 70;\ndo\n\tip link add link ens2 name ipv_$i type ipvlan\n\tip -6 addr add 2002::$i/64 dev ipv_$i\n\tifconfig ipv_$i up\ndone\n\nfor i in 10 20 30 40 50 60;\ndo\n\tip -6 route append 100::/64 encap ip6 dst 2002::$i via 2002::1\ndev ipv_$i metric 100\ndone\n\nip -6 route append 100::/64 via 2002::1 dev ipv_70 metric 100\n\nThis patch fixes it by adding nexthop_len of every siblings using\nrt6_nh_nlmsg_size().","modified":"2026-03-20T12:33:11.680259Z","published":"2025-10-01T11:42:46.279Z","related":["SUSE-SU-2025:4189-1"],"database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/53xxx/CVE-2023-53477.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/4cc59f386991ec9374cb4bc83dbe1c0b5a95033f"},{"type":"WEB","url":"https://git.kernel.org/stable/c/aa75d826c221e8d48607aef33836cf872a159cf1"},{"type":"WEB","url":"https://git.kernel.org/stable/c/aba298b35619213ca787d08d472049627d8cd012"},{"type":"WEB","url":"https://git.kernel.org/stable/c/da26369377f0b671c14692e2d65ceb38131053e1"},{"type":"WEB","url":"https://git.kernel.org/stable/c/dcdddb5f490890d058ea1f194d661219e92fe88d"},{"type":"WEB","url":"https://git.kernel.org/stable/c/e11e4d524eba2d3c8fdf897d7ce3853f7573bae9"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/53xxx/CVE-2023-53477.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2023-53477"},{"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":"beb1afac518dec5a15dc92ba8f0ca016dcf457b4"},{"fixed":"aba298b35619213ca787d08d472049627d8cd012"},{"fixed":"da26369377f0b671c14692e2d65ceb38131053e1"},{"fixed":"dcdddb5f490890d058ea1f194d661219e92fe88d"},{"fixed":"e11e4d524eba2d3c8fdf897d7ce3853f7573bae9"},{"fixed":"aa75d826c221e8d48607aef33836cf872a159cf1"},{"fixed":"4cc59f386991ec9374cb4bc83dbe1c0b5a95033f"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2023-53477.json"}}],"schema_version":"1.7.5"}