# CVE-2026-89573: dm array: reject an array block whose value size is not the caller's

> A flaw in the Linux kernel dm-cache allows attackers to cause memory corruption via crafted metadata, potentially leading to code execution or privilege escalation.

- **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:** 11 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-100521, BELL-CVE-2026-89573, DEBIAN-CVE-2026-89573, GHSA-pg3h-8qxx-35hj, UBUNTU-CVE-2026-89573

## What is CVE-2026-89573?

CVE-2026-89573 is a high-severity memory corruption vulnerability in Linux, published on 11 Sep 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 array: reject an array block whose value size is not the caller's

array_block_check() can only compare the header against itself, so a block
with value_size 4 and max_entries 1018 is internally consistent and passes.
dm-cache keeps two arrays -- mappings at 8 bytes and hints at 4 -- and the
roots for both live in the superblock. Point the mappings root at a hint
block and __load_mappings() walks it through an info whose value size is 8,
so element_at() strides 8 bytes over 4-byte entries and reaches offset 8160
of a 4096-byte block.

get_ablock() and __shadow_ablock() are the two places that hold the block
and the caller at once. Reject there when the two value sizes disagree.
Arrays only ever read their own blocks, so this fires on crafted metadata
only.

## Which versions are affected by CVE-2026-89573?


## How do I fix CVE-2026-89573?

Apply the vendor's patch.

## Is CVE-2026-89573 being exploited?

There is no known exploitation of CVE-2026-89573 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-89573 and fix it if it is affected.

What it is: CVE-2026-89573 is a high-severity memory corruption vulnerability in Linux, published on 11 Sep 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-2026-89573 in the wild and no public exploit code.

Affected product: Linux. 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-2026-89573/ (Markdown: https://insights.sbomify.com/CVE-2026-89573/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-89573
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-89573
- OSV: https://osv.dev/vulnerability/CVE-2026-89573

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-89573/
Summaries are generated and may contain mistakes; the official description above is the record.