# CVE-2026-90327: phonet: pep: do not write beyond optlen in getsockopt

> A local attacker can trigger a buffer overflow in the Linux kernel Phonet protocol via getsockopt, potentially leaking memory or causing a crash.

- **Severity:** Not scored
- **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:** Yes
- **Published:** 17 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-102635, BELL-CVE-2026-90327, DEBIAN-CVE-2026-90327, GHSA-j842-pq84-9gpj, UBUNTU-CVE-2026-90327

## What is CVE-2026-90327?

CVE-2026-90327 is a memory corruption vulnerability in Linux, published on 17 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:

phonet: pep: do not write beyond optlen in getsockopt

pep_getsockopt() clamps the reported length to the caller's buffer with
min_t(), but then stores the value with put_user(val, (int __user *)
optval), which always writes sizeof(int) bytes. A getsockopt() call with
an optlen smaller than sizeof(int) thus reports the clamped length yet
writes a full int, one to three bytes past the user buffer.

Write the value with copy_to_user() bounded by len, so at most optlen
bytes are copied, matching the length reported back to userspace.

## Which versions are affected by CVE-2026-90327?


## How do I fix CVE-2026-90327?

Apply the vendor's patch.

## Is CVE-2026-90327 being exploited?

There is no known exploitation of CVE-2026-90327 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-90327 and fix it if it is affected.

What it is: CVE-2026-90327 is a memory corruption vulnerability in Linux, published on 17 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-2026-90327 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-2026-90327/ (Markdown: https://insights.sbomify.com/CVE-2026-90327/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-90327
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-90327
- OSV: https://osv.dev/vulnerability/CVE-2026-90327

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-90327/
Summaries are generated and may contain mistakes; the official description above is the record.