# CVE-2026-80960: dm-pcache: validate on-media seg_num against the cache device size

> A local attacker with CAP_SYS_ADMIN can trigger an out-of-bounds write in the Linux kernel dm-pcache driver, potentially leading to code execution or privilege escalation.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **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-2026-80960, DEBIAN-CVE-2026-80960, GHSA-5phx-c495-rgx5, UBUNTU-CVE-2026-80960

## What is CVE-2026-80960?

CVE-2026-80960 is a memory corruption 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: validate on-media seg_num against the cache device size

seg_num is read from the crc32c-only superblock, so whoever supplies the
cache device on a table load (CAP_SYS_ADMIN) controls it. It sizes
cache->segments[] and is the value every later on-media segment id is
bounded against, yet it is never checked against the device. Because
cache_dev->mapping is the direct map of the pmem, CACHE_DEV_SEGMENT() for
a segment id past the device resolves to ordinary kernel memory beyond
the mapping; a new-cache init reaching such an id has cache_seg_init() ->
cache_dev_zero_range() memset() 12 KiB over that memory -- an
out-of-bounds write into the kernel heap at table load. A zero seg_num
makes the segment allocations ZERO_SIZE_PTR.

Reject a seg_num that is zero, larger than the device can hold, or larger
than PCACHE_CACHE_SEGS_MAX before it is used.

## Which versions are affected by CVE-2026-80960?


## How do I fix CVE-2026-80960?

Apply the vendor's patch.

## Is CVE-2026-80960 being exploited?

There is no known exploitation of CVE-2026-80960 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-80960 and fix it if it is affected.

What it is: CVE-2026-80960 is a memory corruption 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-2026-80960 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-2026-80960/ (Markdown: https://insights.sbomify.com/CVE-2026-80960/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-80960
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-80960
- OSV: https://osv.dev/vulnerability/CVE-2026-80960

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-80960/
Summaries are generated and may contain mistakes; the official description above is the record.