---
id: "CVE-2026-98867"
kind: "vulnerability"
aliases: ["CVE-2026-98867"]
title: "Linux kernel dm-pcache: unchecked key offset can write outside a kernel array"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "infrastructure"
products: []
ecosystems: []
tags: ["dm-pcache", "infrastructure", "linux-kernel", "persistent-memory", "self-hosted"]
not_affected_if: ["dm-pcache-not-used"]
published_at: "2026-10-18T16:17:41+00:00"
first_seen_at: "2026-10-23T21:57:17+00:00"
updated_at: "2026-10-25T05:12:47+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98867", "first_seen_at": "2026-10-23T21:57:17+00:00"}]
---

# Linux kernel dm-pcache: unchecked key offset can write outside a kernel array

The Linux kernel's dm-pcache device-mapper cache reads a key's logical offset from persistent memory and uses it to index an array without a bounds check. A crafted or corrupted cache device can make the kernel write through an out-of-range pointer during replay.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- unknown

## Fix

- unknown

## Timeline

- 2026-10-23T21:57:17+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-98867

## From the sources

In the Linux kernel, the following vulnerability has been resolved:

dm-pcache: bound the logical key offset from persistent memory

cache_key_decode() takes a key's logical off from the cache device and
later indexes req_key_tree->subtrees[] by it in get_subtree(). An off
past the device forms a subtree pointer outside the array, which
rb_insert() writes through during replay.

Reject a key of zero length, or whose off+len (computed in 64 bits)
exceeds the device size, before it is used.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_