CVE-2026-72429 ipv6: ioam: fix type confusion of dst_entry
A type confusion vulnerability in the Linux kernel IPv6 IOAM module allows invalid pointer access, potentially leading to code execution or denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-72429?
CVE-2026-72429 is a critical memory corruption vulnerability in Linux, published on 15 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
ipv6: ioam: fix type confusion of dst_entry
IOAM uses a dummy dst_entry(null_dst) to mark that the destination should not be changed after the transformation. This dst is stored in the IOAM lwt state and may be passed to dst_cache_set_ip6().
However, the IPv6 dst cache path eventually calls rt6_get_cookie(), which treats the dst_entry as part of a struct rt6_info. Since the null_dst was embedded directly as a struct dst_entry in struct ioam6_lwt, this resulted in an invalid cast and rt6_get_cookie() reading fields from the wrong object.
In practice, the wrong cookie is not used while dst->obsolete is zero, but rt6_get_cookie() may also access per-cpu value when rt->sernum is zero. In this case, rt->sernum aliases ioam6_lwt::cache::reset_ts, which can become zero, making this a potential invalid pointer access.
Fix this by embedding a full struct rt6_info for the dummy IPv6 route and passing its dst member to the dst APIs.
Which versions are affected by CVE-2026-72429?
How do I fix CVE-2026-72429?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-72429 being exploited?
There is no known exploitation of CVE-2026-72429 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-72429, DEBIAN-CVE-2026-72429, GHSA-34fv-pgg7-6wvm, UBUNTU-CVE-2026-72429.