CVE-2026-80962: dm-pcache: validate geometry fields from on-disk cache_info

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-09-11 · updated 2026-10-19

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.

Affected products

Linux kernel: 6.18 — fixed in 7.3

How to fix

Upgrade to a fixed version: Linux kernel 7.3. Check the vendor advisory for mitigations.

References

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