# CVE-2026-80993: net: phylink: correctly validate returned PCS in phylink_inband_caps

> A missing error check in the Linux kernel's phylink subsystem allows a local attacker to trigger a kernel panic via a null pointer dereference.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 11 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-80993, DEBIAN-CVE-2026-80993, GHSA-v77c-jw3g-56gh, UBUNTU-CVE-2026-80993

## What is CVE-2026-80993?

CVE-2026-80993 is a vulnerability in Linux, published on 11 Sep 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:

net: phylink: correctly validate returned PCS in phylink_inband_caps

In phylink_inband_caps(), the PCS returned by mac_select_pcs is only
checked if NULL but mac_select_pcs can also return an error pointer.

This can cause a kernel panic as phylink_pcs_inband_caps() only checks
if passed PCS is not NULL and directly dereference ops from the phylink_pcs
struct.

Use the IS_ERR_OR_NULL macro to address both case where the returned
PCS can be NULL or an error pointer and prevent a kernel panic.

## Which versions are affected by CVE-2026-80993?


## How do I fix CVE-2026-80993?

Apply the vendor's patch.

## Is CVE-2026-80993 being exploited?

There is no known exploitation of CVE-2026-80993 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-80993 and fix it if it is affected.

What it is: CVE-2026-80993 is a vulnerability in Linux, published on 11 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-80993 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-2026-80993/ (Markdown: https://insights.sbomify.com/CVE-2026-80993/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-80993
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-80993
- OSV: https://osv.dev/vulnerability/CVE-2026-80993

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-80993/
Summaries are generated and may contain mistakes; the official description above is the record.