CVE-2026-99071 ipv4: do not warn on route notification size race
- Exploited in the wild
- Not known
- Fix
- Available
What is CVE-2026-99071?
CVE-2026-99071 is a vulnerability in Linux, published on 23 Oct 2026.
Official description
In the Linux kernel, the following vulnerability has been resolved:
ipv4: do not warn on route notification size race
Commit 680aea08e78c ("net: ipv4: Emit notification when fib hardware flags are changed") added asynchronous route notifications for hardware flag changes.
fib_alias_hw_flags_set() sizes the skb with fib_nlmsg_size() and later fills it with fib_dump_info() while holding only RCU. With nexthop compatibility mode enabled, a concurrent replacement can grow the group between these independent snapshots. fib_dump_info() can then legitimately return -EMSGSIZE, so the warning does not prove a sizing bug.
Remove the warning. The existing error path still frees the skb and reports the error to listeners.
Which versions are affected by CVE-2026-99071?
How do I fix CVE-2026-99071?
Upgrade to a fixed version.
Is CVE-2026-99071 being exploited?
There is no known exploitation of CVE-2026-99071 in the wild and no public exploit code.
Sources
Also known as AZL-110963, BELL-CVE-2026-99071, DEBIAN-CVE-2026-99071, GHSA-66g6-r4v9-4xgm, UBUNTU-CVE-2026-99071.