# CVE-2026-98868: Linux kernel dm-pcache buffer over-read in segment processing

Source: https://junglewise.ai/threats/cve-2026-98868-in-the-linux-kernel-the-following-vulnerability-has-been-resolved  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-18. Updated: 2026-10-18  
License: CC BY 4.0 with a link back

CVE-2026-98868 · Severity: info · Published 2026-10-18

The Linux kernel's dm-pcache (persistent cache) component can be tricked into reading past the end of a memory segment when processing specially crafted cache key sets. A local attacker with the ability to forge cache metadata could trigger a kernel crash (denial of service) or potentially leak sensitive kernel memory.

Technologies: [Linux Kernel](https://junglewise.ai/threats/technologies/kernel). Vendors: [Linux](https://junglewise.ai/threats/vendors/linux).

## Quick answers

**Is CVE-2026-98868 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-98868 being exploited in the wild.

**How severe is CVE-2026-98868?** Informational severity, published 18 October 2026.

**Which products and versions are affected?** Linux Kernel dm-pcache component; patched from commit 7ac1f10f987a2ffae4aecf0e2ceca8f552b665cb onwards.

**Is there a fix for CVE-2026-98868?** A patch was published on 2026-09-14. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-98868 attacked?** It is attacked with local access, in an operating system.

**Am I affected by CVE-2026-98868?** Check whether you run Linux Kernel at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The vulnerability exists in the cache_replay(), writeback worker, and garbage collector functions in drivers/md/dm-pcache. A malformed key_num field in an on-media key set structure causes get_kset_onmedia_size() to return a value exceeding the remaining segment space, leading to an out-of-bounds read and a BUG_ON crash in cache_pos_advance(). The fix adds a bounds check comparing the calculated kset size against cache_seg_remain() before processing.

## Affected products

- Linux Linux kernel dm-pcache component; patched from commit 7ac1f10f987a2ffae4aecf0e2ceca8f552b665cb onwards

## Timeline

- 2026-07-17: disclosed
- 2026-09-14: patched

## References

- [https://git.kernel.org/stable/c/01a700e9278da5706c865b9ca3ae70fdb7b4531d](https://git.kernel.org/stable/c/01a700e9278da5706c865b9ca3ae70fdb7b4531d)
- [https://git.kernel.org/stable/c/7ac1f10f987a2ffae4aecf0e2ceca8f552b665cb](https://git.kernel.org/stable/c/7ac1f10f987a2ffae4aecf0e2ceca8f552b665cb)

## Related threats

- [Linux kernel dm-pcache out-of-bounds write in cache key handling](https://junglewise.ai/threats/cve-2026-98867-in-the-linux-kernel-the-following-vulnerability-has-been-resolved)
- [Linux kernel use-after-free in scheduler cache group access](https://junglewise.ai/threats/cve-2026-98866-in-the-linux-kernel-the-following-vulnerability-has-been-resolved)
- [Linux kernel sched_ext deadlock in ops.dequeue() with DSQ lock](https://junglewise.ai/threats/cve-2026-98865-in-the-linux-kernel-the-following-vulnerability-has-been-resolved)
- [Linux kernel sched_ext task reenqueue state synchronization](https://junglewise.ai/threats/cve-2026-98864-in-the-linux-kernel-the-following-vulnerability-has-been-resolved)
- [Linux kernel KVM nested state pages memory safety issue](https://junglewise.ai/threats/cve-2026-98863-in-the-linux-kernel-the-following-vulnerability-has-been-resolved)