CVE-2026-74657
Description
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.
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
No mitigations published for this CVE yet.
The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.
Propose a mitigation on Community Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here withsource_tier=community-verified.
References
- https://git.kernel.org/stable/c/0f0ca602941d0a81ae9514943ca06c55159c6385
- https://git.kernel.org/stable/c/4a5dfbae5179f6574695012a980476254df2d295
- https://git.kernel.org/stable/c/4ff9548d84945d2cbf9e4c207288063a200ea397
- https://git.kernel.org/stable/c/5307a53599fa762c06e475ee4a375252074fd324
- https://git.kernel.org/stable/c/7f80ad373ce4a7af5367ff273cea0f16e91387f3
- https://git.kernel.org/stable/c/9b22f13524fa0de0d963bbd3002df6c28bae3395
- https://git.kernel.org/stable/c/a59edda6eda1252340354322d8ab318b2e9052fb
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.