# CVE-2026-99079: net/mlx5e: Prevent stale XSK buffer release on refill retry


- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 23 Oct 2026
- **Updated:** 24 Oct 2026
- **Also known as:** AZL-110978, BELL-CVE-2026-99079, DEBIAN-CVE-2026-99079, GHSA-7w5x-75mg-qr73, UBUNTU-CVE-2026-99079

## 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.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-99079 and fix it if it is affected.

What it is: CVE-2026-99079 is a critical vulnerability in Linux, published on 23 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-99079 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-99079/ (Markdown: https://insights.sbomify.com/CVE-2026-99079/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-99079
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-99079
- OSV: https://osv.dev/vulnerability/CVE-2026-99079

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-99079/
Summaries are generated and may contain mistakes; the official description above is the record.