CVE-2026-99079 net/mlx5e: Prevent stale XSK buffer release on refill retry
- Exploited in the wild
- Not known
- Fix
- Available
What is CVE-2026-99079?
CVE-2026-99079 is a critical vulnerability in Linux, published on 23 Oct 2026.
Official description
In the Linux kernel, the following vulnerability has been resolved:
net/mlx5e: Prevent stale XSK buffer release on refill retry
When an XDP redirect to an AF_XDP socket fails because its RX ring is full, the XSK core frees the buffer. During the subsequent batched refill of a legacy cyclic RQ, mlx5e also releases the WQE's XSK buffer before allocating a replacement. If that refill succeeds only partially, a WQE left without a replacement retains its old buffer pointer.
The buffer can meanwhile be allocated to another WQE. A later refill retry can then free the live buffer through the stale pointer and publish the same UMEM frame twice.
Mark the WQE as released immediately after the driver-side free. The flag is already cleared when a replacement buffer is assigned, so refill retries no longer release stale pointers.
The failure is silent and produces no kernel warning or splat. A standalone legacy cyclic-RQ zero-copy libxsk reproducer, using 64-byte UDP traffic offered at 12 Mpps, detected it: stock stopped after 2,854,914 packets in 4.094 seconds, with 4,542 xdp_rx_ring_full events and 64 ownership/double-publication errors. With this change it processed 356,904,225 packets in 30 seconds despite 571,405 xdp_rx_ring_full events, with no ownership or data errors.
Which versions are affected by CVE-2026-99079?
How do I fix CVE-2026-99079?
Upgrade to a fixed version.
Is CVE-2026-99079 being exploited?
There is no known exploitation of CVE-2026-99079 in the wild and no public exploit code.
Sources
Also known as AZL-110978, BELL-CVE-2026-99079, DEBIAN-CVE-2026-99079, GHSA-7w5x-75mg-qr73, UBUNTU-CVE-2026-99079.