CVE-2026-74709 xsk: clear metadata pointer when no timestamp is requested
A local attacker can trigger a race condition in the Linux kernel XSK subsystem to write unauthorized timestamps into memory, potentially corrupting data.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-74709?
CVE-2026-74709 is a memory corruption vulnerability in Linux, published on 22 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
xsk: clear metadata pointer when no timestamp is requested
User space can change metadata flags after request processing. Rereading them during completion can therefore make the kernel write a timestamp that was not requested when the packet was submitted.
Clear the metadata pointer during request processing unless timestamp completion is requested. Completion handling can then use the pointer itself instead of rereading the flags.
On the mlx5 multi-packet WQE path metadata is evaluated per batch: xsk_tx_metadata_request() runs only for the descriptor that starts a session, just like the checksum offload that is applied once through the shared WQE. Only that descriptor's pointer is reset, so completion handling can record a timestamp for the other descriptors of the session regardless of their own XDP_TXMD_FLAGS_TIMESTAMP bit. The write stays inside the metadata area; the single-WQE, other zero-copy, and generic paths reset the pointer per descriptor and are unaffected.
Which versions are affected by CVE-2026-74709?
How do I fix CVE-2026-74709?
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-2026-74709 being exploited?
There is no known exploitation of CVE-2026-74709 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-74709, DEBIAN-CVE-2026-74709, GHSA-gg32-fqwc-p469, UBUNTU-CVE-2026-74709.