CVE-2026-72249 netfilter: flowtable: use dst in this direction when pushing IPIP header
A Linux kernel netfilter flowtable bug causes incorrect headroom calculation when pushing IPIP headers, potentially leading to memory corruption or crashes.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-72249?
CVE-2026-72249 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:
netfilter: flowtable: use dst in this direction when pushing IPIP header
When pushing the IPIP header, the route of the other direction is used to calculate the headroom, use the route in this direction. Accessing the other tuple to set the IP source and destination is fine because this tuple does not provide such information to avoid storing redundant information. However, this tuple already provides the dst for this direction, this went unnoticed because this bug affects headroom and iph->frag_off only at this stage.
Which versions are affected by CVE-2026-72249?
How do I fix CVE-2026-72249?
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-2026-72249 being exploited?
There is no known exploitation of CVE-2026-72249 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-72249, GHSA-3xpj-q99r-5475, UBUNTU-CVE-2026-72249.