# CVE-2026-53265: dm cache policy smq: check allocation under invalidate lock

> A race condition in the Linux kernel's dm cache policy allows concurrent invalidators to corrupt data structures, potentially causing crashes or data corruption.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 25 Jun 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-90977, BELL-CVE-2026-53265, DEBIAN-CVE-2026-53265, GHSA-257g-7vrp-j9f8, ROOT-OS-DEBIAN-12-CVE-2026-53265, ROOT-OS-UBUNTU-2204-CVE-2026-53265, ROOT-OS-UBUNTU-2404-CVE-2026-53265, UBUNTU-CVE-2026-53265

## What is CVE-2026-53265?

CVE-2026-53265 is a high-severity vulnerability in Linux kernel, published on 25 Jun 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

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

dm cache policy smq: check allocation under invalidate lock

commit 2d1f7b65f5de ("dm cache policy smq: fix missing locks in
invalidating cache blocks") added mq->lock around the destructive part of
smq_invalidate_mapping(), but left the e->allocated check outside the
critical section.

That leaves a check-then-act race. Two concurrent invalidators can both
observe e->allocated as true before either of them takes mq->lock. The
first invalidator that acquires the lock removes the entry from the
queues and hash table and then calls free_entry(), which clears
e->allocated and puts the entry back on the free list. The second
invalidator can then acquire mq->lock and continue with the stale result
of the unlocked check.

This can corrupt the SMQ queues or hash table by deleting an entry that
is no longer on those structures. It can also hit the allocation check in
free_entry() when the same entry is freed again.

Move the allocation check under mq->lock so the predicate and the
destructive operations are serialized by the same lock.

Weakness: CWE-362 (Concurrent Execution using Shared Resource with Improper Synchronization)

## Which versions are affected by CVE-2026-53265?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-53265?

Apply the vendor's patch.

## Is CVE-2026-53265 being exploited?

There is no known exploitation of CVE-2026-53265 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-53265 and fix it if it is affected.

What it is: CVE-2026-53265 is a high-severity vulnerability in Linux kernel, published on 25 Jun 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-53265 in the wild and no public exploit code.

Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-53265/ (Markdown: https://insights.sbomify.com/CVE-2026-53265/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-53265
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-53265
- OSV: https://osv.dev/vulnerability/CVE-2026-53265

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-53265/
Summaries are generated and may contain mistakes; the official description above is the record.