# CVE-2026-90086: xsk: honor XDP_TX_METADATA in zero-copy path

> A flaw in the Linux kernel's XDP zero-copy path allows unrequested timestamp overwrites in TX metadata, potentially corrupting data.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 17 Sep 2026
- **Updated:** 21 Oct 2026
- **Also known as:** BELL-CVE-2026-90086, DEBIAN-CVE-2026-90086, GHSA-5vhq-jqrp-ph25, UBUNTU-CVE-2026-90086

## What is CVE-2026-90086?

CVE-2026-90086 is a vulnerability in Linux, published on 17 Sep 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:

xsk: honor XDP_TX_METADATA in zero-copy path

The zero-copy path reads TX metadata whenever the UMEM has metadata space,
even if the descriptor does not set XDP_TX_METADATA. Pass descriptor
options through the metadata helpers and ignore metadata unless the option
is set.

This does not fix the existing per-WQE metadata handling for mlx5 MPWQEs.
Only the descriptor that starts a session passes through
xsk_tx_metadata_request() and configures offload state shared by the batch.
Metadata on descriptors joining an open session is therefore not validated
and does not configure its requested offloads. In addition, a non-NULL
metadata pointer from such a descriptor is treated as a timestamp
completion request even when XDP_TXMD_FLAGS_TIMESTAMP is not set, so its
metadata union can be overwritten with an unrequested timestamp. Fixing
mixed metadata states within one MPWQE requires a separate change.

## Which versions are affected by CVE-2026-90086?


## How do I fix CVE-2026-90086?

Apply the vendor's patch.

## Is CVE-2026-90086 being exploited?

There is no known exploitation of CVE-2026-90086 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-90086 and fix it if it is affected.

What it is: CVE-2026-90086 is a vulnerability in Linux, published on 17 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-90086 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-2026-90086/ (Markdown: https://insights.sbomify.com/CVE-2026-90086/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-90086
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-90086
- OSV: https://osv.dev/vulnerability/CVE-2026-90086

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-90086/
Summaries are generated and may contain mistakes; the official description above is the record.