CVE-2026-74657ipv4: Fix fib_nlmsg_size() for RTA_VIA nexthops
Updated under an hour ago ()
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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.
- CVSS
- Not yet scored
- Weakness (CWE)
- Not given
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Linux
- NVD analysis
- Received
- Record last updated
- Aug 27, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Linux Linux linux:linux (from the name) | from d15662682db232da77136cd348f4c9df312ca6f9 before 57195f0ab5cfbb5ee0864e5aff15ceb48f5a5e28; from d15662682db232da77136cd348f4c9df312ca6f9 before 0f0ca602941d0a81ae9514943ca06c55159c6385; from d15662682db232da77136cd348f4c9df312ca6f9 before 5307a53599fa762c06e475ee4a375252074fd324; from d15662682db232da77136cd348f4c9df312ca6f9 before 7f80ad373ce4a7af5367ff273cea0f16e91387f3; from d15662682db232da77136cd348f4c9df312ca6f9 before 4a5dfbae5179f6574695012a980476254df2d295; from d15662682db232da77136cd348f4c9df312ca6f9 before a59edda6eda1252340354322d8ab318b2e9052fb; from d15662682db232da77136cd348f4c9df312ca6f9 before 9b22f13524fa0de0d963bbd3002df6c28bae3395; from d15662682db232da77136cd348f4c9df312ca6f9 before 4ff9548d84945d2cbf9e4c207288063a200ea397 | CNA record |
References
- https://git.kernel.org/stable/c/57195f0ab5cfbb5ee0864e5aff15ceb48f5a5e28
- https://git.kernel.org/stable/c/0f0ca602941d0a81ae9514943ca06c55159c6385
- https://git.kernel.org/stable/c/5307a53599fa762c06e475ee4a375252074fd324
- https://git.kernel.org/stable/c/7f80ad373ce4a7af5367ff273cea0f16e91387f3
- https://git.kernel.org/stable/c/4a5dfbae5179f6574695012a980476254df2d295
- https://git.kernel.org/stable/c/a59edda6eda1252340354322d8ab318b2e9052fb
- https://git.kernel.org/stable/c/9b22f13524fa0de0d963bbd3002df6c28bae3395
- https://git.kernel.org/stable/c/4ff9548d84945d2cbf9e4c207288063a200ea397
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.