CVE-2023-53477
Full vulnerability record from the local CVENow database.
Description
In the Linux kernel, the following vulnerability has been resolved: ipv6: Add lwtunnel encap size of all siblings in nexthop calculation In function rt6_nlmsg_size(), the length of nexthop is calculated by multipling the nexthop length of fib6_info and the number of siblings. However if the fib6_info has no lwtunnel but the siblings have lwtunnels, the nexthop length is less than it should be, and it will trigger a warning in inet6_rt_notify() as follows: WARNING: CPU: 0 PID: 6082 at net/ipv6/route.c:6180 inet6_rt_notify+0x120/0x130 ...... Call Trace: <TASK> fib6_add_rt2node+0x685/0xa30 fib6_add+0x96/0x1b0 ip6_route_add+0x50/0xd0 inet6_rtm_newroute+0x97/0xa0 rtnetlink_rcv_msg+0x156/0x3d0 netlink_rcv_skb+0x5a/0x110 netlink_unicast+0x246/0x350 netlink_sendmsg+0x250/0x4c0 sock_sendmsg+0x66/0x70 ___sys_sendmsg+0x7c/0xd0 __sys_sendmsg+0x5d/0xb0 do_syscall_64+0x3f/0x90 entry_SYSCALL_64_after_hwframe+0x72/0xdc This bug can be reproduced by script: ip -6 addr add 2002::2/64 dev ens2 ip -6 route add 100::/64 via 2002::1 dev ens2 metric 100 for i in 10 20 30 40 50 60 70; do ip link add link ens2 name ipv_$i type ipvlan ip -6 addr add 2002::$i/64 dev ipv_$i ifconfig ipv_$i up done for i in 10 20 30 40 50 60; do ip -6 route append 100::/64 encap ip6 dst 2002::$i via 2002::1 dev ipv_$i metric 100 done ip -6 route append 100::/64 via 2002::1 dev ipv_70 metric 100 This patch fixes it by adding nexthop_len of every siblings using rt6_nh_nlmsg_size().
Severity
MEDIUM
CVSS score
5.5
(v3.1)
Vulnerability status
Analyzed
Source identifier
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Published
2025-10-01 12:15:50.110000
Last modified
2026-11-05 21:17:22.190000
View original CVE JSON
{
"id": "CVE-2023-53477",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"published": "2025-10-01T12:15:50.110",
"lastModified": "2026-11-05T21:17:22.190",
"vulnStatus": "Analyzed",
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "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 <TASK>\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()."
}
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"source": "[email protected]",
"type": "Primary",
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"baseScore": 5.5,
"baseSeverity": "MEDIUM",
"attackVector": "LOCAL",
"attackComplexity": "LOW",
"privilegesRequired": "LOW",
"userInteraction": "NONE",
"scope": "UNCHANGED",
"confidentialityImpact": "NONE",
"integrityImpact": "NONE",
"availabilityImpact": "HIGH"
},
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"id": "CVE-2023-53477",
"options": [
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{
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"source": "[email protected]",
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"description": [
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