CVE-2023-53477 (GCVE-0-2023-53477)
Vulnerability from cvelistv5 – Published: 2025-10-01 11:42 – Updated: 2025-10-01 11:42
VLAI?
Title
ipv6: Add lwtunnel encap size of all siblings in nexthop calculation
Summary
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 ?
No CVSS data available.
Assigner
References
Impacted products
| Vendor | Product | Version | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Linux | Linux |
Affected:
beb1afac518dec5a15dc92ba8f0ca016dcf457b4 , < aba298b35619213ca787d08d472049627d8cd012
(git)
Affected: beb1afac518dec5a15dc92ba8f0ca016dcf457b4 , < da26369377f0b671c14692e2d65ceb38131053e1 (git) Affected: beb1afac518dec5a15dc92ba8f0ca016dcf457b4 , < dcdddb5f490890d058ea1f194d661219e92fe88d (git) Affected: beb1afac518dec5a15dc92ba8f0ca016dcf457b4 , < e11e4d524eba2d3c8fdf897d7ce3853f7573bae9 (git) Affected: beb1afac518dec5a15dc92ba8f0ca016dcf457b4 , < aa75d826c221e8d48607aef33836cf872a159cf1 (git) Affected: beb1afac518dec5a15dc92ba8f0ca016dcf457b4 , < 4cc59f386991ec9374cb4bc83dbe1c0b5a95033f (git) |
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|
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{
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"status": "unaffected",
"version": "5.10.173",
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"version": "5.15.100",
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{
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"version": "6.1.18",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.2.*",
"status": "unaffected",
"version": "6.2.5",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "6.3",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
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],
"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 \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()."
}
],
"providerMetadata": {
"dateUpdated": "2025-10-01T11:42:46.279Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/aba298b35619213ca787d08d472049627d8cd012"
},
{
"url": "https://git.kernel.org/stable/c/da26369377f0b671c14692e2d65ceb38131053e1"
},
{
"url": "https://git.kernel.org/stable/c/dcdddb5f490890d058ea1f194d661219e92fe88d"
},
{
"url": "https://git.kernel.org/stable/c/e11e4d524eba2d3c8fdf897d7ce3853f7573bae9"
},
{
"url": "https://git.kernel.org/stable/c/aa75d826c221e8d48607aef33836cf872a159cf1"
},
{
"url": "https://git.kernel.org/stable/c/4cc59f386991ec9374cb4bc83dbe1c0b5a95033f"
}
],
"title": "ipv6: Add lwtunnel encap size of all siblings in nexthop calculation",
"x_generator": {
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}
}
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"cveMetadata": {
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"assignerShortName": "Linux",
"cveId": "CVE-2023-53477",
"datePublished": "2025-10-01T11:42:46.279Z",
"dateReserved": "2025-10-01T11:39:39.401Z",
"dateUpdated": "2025-10-01T11:42:46.279Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.1"
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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