Quick answers
- Is CVE-2026-99074 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-99074 being exploited in the wild.
- How severe is CVE-2026-99074?
- Informational severity, published 23 October 2026.
- Which products and versions are affected?
- Linux kernel Versions with commit 7d3f3b4367f3 and later, prior to fix commit 6619e01855e65ef35723685a557e3eb106f4ecf5.
- Is there a fix for CVE-2026-99074?
- A patch was published on 2026-10-06: Fix committed upstream Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-99074 attacked?
- It is attacked with local access, in an operating system.
- Am I affected by CVE-2026-99074?
- Check whether you run Linux kernel at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
A race condition exists in __ip_rt_update_pmtu() where fib_info_num_path() and fib_info_nhc() independently load nexthop group data protected only by RCU. If a concurrent nexthop group replacement shrinks the group after the loop accepts an index, fib_info_nhc() returns NULL and update_or_create_fnhe() dereferences the NULL pointer. The fix adds a NULL check to break the loop when an indexed path becomes absent. This requires CAP_NET_ADMIN in a network namespace, which unprivileged users can obtain in their own user/network namespace.
Affected products
- Linux kernel Versions with commit 7d3f3b4367f3 and later, prior to fix commit 6619e01855e65ef35723685a557e3eb106f4ecf5
Timeline
- 2026-10-23: disclosed
- 2026-10-06: patched: Fix committed upstream
- 2026-10-02: other: Fix authored