---
id: CVE-2026-80960
title: 'dm-pcache: validate on-media seg_num against the cache device size'
summary: |-
  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 loa…
severity: medium
cvss: 5.5
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'
cvssSource: vendor
cwe:
  - CWE-787
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 1d57628ff95b32d5cfa8d8f50e07690c161e9cf0 <
    91b93fe5cf4d62d5ecc642a6c8f15a3c11b00e3c
  - >-
    Linux >= 1d57628ff95b32d5cfa8d8f50e07690c161e9cf0 <
    e889c0ee81165fc90aad2979b51f930f77895703
  - >-
    Linux >= 1d57628ff95b32d5cfa8d8f50e07690c161e9cf0 <
    62d92e45abe9e087370f9fc5d876b95673aced34
  - Linux 6.18
published: '2026-09-11'
updated: '2026-10-19'
sourceUpdated: '2026-10-19T08:45:44.213Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-80960'
references:
  - url: 'https://git.kernel.org/stable/c/91b93fe5cf4d62d5ecc642a6c8f15a3c11b00e3c'
  - url: 'https://git.kernel.org/stable/c/e889c0ee81165fc90aad2979b51f930f77895703'
  - url: 'https://git.kernel.org/stable/c/62d92e45abe9e087370f9fc5d876b95673aced34'
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-80960.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-80960'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2532483'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-80960'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-80960'
  - url: >-
      https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-80960.mbox
tags:
  - cve.org
  - csaf
  - vex
  - red-hat
epss: 0.00206
epssPercentile: 0.1061
ingestedAt: '2026-09-14T00:35:28.532Z'
---

## Overview

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.

## Affected

- `Linux >= 1d57628ff95b32d5cfa8d8f50e07690c161e9cf0 < 91b93fe5cf4d62d5ecc642a6c8f15a3c11b00e3c`
- `Linux >= 1d57628ff95b32d5cfa8d8f50e07690c161e9cf0 < e889c0ee81165fc90aad2979b51f930f77895703`
- `Linux >= 1d57628ff95b32d5cfa8d8f50e07690c161e9cf0 < 62d92e45abe9e087370f9fc5d876b95673aced34`
- `Linux 6.18`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Vendor advisories

- **Red Hat VEX** · Moderate · updated 2026-09-14 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-80960.json)