# CVE-2026-80958: dm-pcache: clamp the tail kset read to the segment data region

> A local attacker can read sensitive kernel memory by triggering a buffer over-read in the dm-pcache module's tail kset handling.

- **Severity:** High 7.1 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H`)
- **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:** 11 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-80958, DEBIAN-CVE-2026-80958, GHSA-hh69-ghmv-95j7, UBUNTU-CVE-2026-80958

## What is CVE-2026-80958?

CVE-2026-80958 is a high-severity 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:

dm-pcache: clamp the tail kset read to the segment data region

The tail-kset read in cache_replay(), the writeback worker and the GC
worker bounds its length by PCACHE_SEG_SIZE - seg_off, the raw segment
size rather than the data region. A tail near the segment end reads past
the segment data into the following control area.

Clamp the read to cache_seg_remain(), the data region.

## Which versions are affected by CVE-2026-80958?


## How do I fix CVE-2026-80958?

Apply the vendor's patch.

## Is CVE-2026-80958 being exploited?

There is no known exploitation of CVE-2026-80958 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-80958 and fix it if it is affected.

What it is: CVE-2026-80958 is a high-severity 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-2026-80958 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-2026-80958/ (Markdown: https://insights.sbomify.com/CVE-2026-80958/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-80958
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-80958
- OSV: https://osv.dev/vulnerability/CVE-2026-80958

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-80958/
Summaries are generated and may contain mistakes; the official description above is the record.