CVE-2026-74657 (GCVE-0-2026-74657)
Vulnerability from cvelistv5
Published
2026-08-22 15:32
Modified
2026-08-27 12:39
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
ipv4: Fix fib_nlmsg_size() for RTA_VIA nexthops
fib_nlmsg_size() still estimates nexthop space as if every gateway is
encoded as an IPv4 RTA_GATEWAY attribute. IPv4 routes can also carry an
IPv6 gateway, which fib_nexthop_info() dumps as RTA_VIA.
As a result, route notifications can allocate an skb that is too small.
fib_dump_info() then fails with -EMSGSIZE and rtmsg_fib() hits the
WARN_ON() that marks such failures as a fib_nlmsg_size() bug. With
panic_on_warn set, this becomes a kernel panic.
Mirror the actual nexthop dump layout in fib_nlmsg_size(): account for
IPv6 nexthop gateways dumped as RTA_VIA, for the no-header rtnexthop
layout used inside RTA_MULTIPATH, and for RTA_FLOW only when it is
actually present.
References
Impacted products
| Vendor | Product | Version | ||
|---|---|---|---|---|
| Linux | Linux |
Version: d15662682db232da77136cd348f4c9df312ca6f9 Version: d15662682db232da77136cd348f4c9df312ca6f9 Version: d15662682db232da77136cd348f4c9df312ca6f9 Version: d15662682db232da77136cd348f4c9df312ca6f9 Version: d15662682db232da77136cd348f4c9df312ca6f9 Version: d15662682db232da77136cd348f4c9df312ca6f9 Version: d15662682db232da77136cd348f4c9df312ca6f9 Version: d15662682db232da77136cd348f4c9df312ca6f9 |
||
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"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nipv4: Fix fib_nlmsg_size() for RTA_VIA nexthops\n\nfib_nlmsg_size() still estimates nexthop space as if every gateway is\nencoded as an IPv4 RTA_GATEWAY attribute. IPv4 routes can also carry an\nIPv6 gateway, which fib_nexthop_info() dumps as RTA_VIA.\n\nAs a result, route notifications can allocate an skb that is too small.\nfib_dump_info() then fails with -EMSGSIZE and rtmsg_fib() hits the\nWARN_ON() that marks such failures as a fib_nlmsg_size() bug. With\npanic_on_warn set, this becomes a kernel panic.\n\nMirror the actual nexthop dump layout in fib_nlmsg_size(): account for\nIPv6 nexthop gateways dumped as RTA_VIA, for the no-header rtnexthop\nlayout used inside RTA_MULTIPATH, and for RTA_FLOW only when it is\nactually present."
}
],
"providerMetadata": {
"dateUpdated": "2026-08-27T12:39:57.259Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
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"references": [
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"url": "https://git.kernel.org/stable/c/57195f0ab5cfbb5ee0864e5aff15ceb48f5a5e28"
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"url": "https://git.kernel.org/stable/c/0f0ca602941d0a81ae9514943ca06c55159c6385"
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"url": "https://git.kernel.org/stable/c/5307a53599fa762c06e475ee4a375252074fd324"
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{
"url": "https://git.kernel.org/stable/c/7f80ad373ce4a7af5367ff273cea0f16e91387f3"
},
{
"url": "https://git.kernel.org/stable/c/4a5dfbae5179f6574695012a980476254df2d295"
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{
"url": "https://git.kernel.org/stable/c/a59edda6eda1252340354322d8ab318b2e9052fb"
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{
"url": "https://git.kernel.org/stable/c/9b22f13524fa0de0d963bbd3002df6c28bae3395"
},
{
"url": "https://git.kernel.org/stable/c/4ff9548d84945d2cbf9e4c207288063a200ea397"
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"title": "ipv4: Fix fib_nlmsg_size() for RTA_VIA nexthops",
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"cveId": "CVE-2026-74657",
"datePublished": "2026-08-22T15:32:31.458Z",
"dateReserved": "2026-08-15T05:44:03.923Z",
"dateUpdated": "2026-08-27T12:39:57.259Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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