# CVE-2026-99037: dm-crypt: reject the lmk IV mode with AEAD ciphers


- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 23 Oct 2026
- **Updated:** 23 Oct 2026
- **Also known as:** AZL-110906, BELL-CVE-2026-99037, DEBIAN-CVE-2026-99037, GHSA-9xmg-p5vw-vprw, UBUNTU-CVE-2026-99037

## What is CVE-2026-99037?

CVE-2026-99037 is a vulnerability in Linux, published on 23 Oct 2026. 

### Official description

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

dm-crypt: reject the lmk IV mode with AEAD ciphers

A "capi:" table line that pairs an AEAD cipher with the lmk IV mode,
for example "capi:gcm(aes)-lmk" with the integrity:28:aead option,
causes an oops when it is loaded. lmk sets tfms_count to 64, but
crypt_alloc_tfms_aead only allocates one transform, so crypt_setkey
reads past the end of the tfms_aead array and calls crypto_aead_setkey
on the values it finds there.

lmk exists for compatibility with Loop-AES, which uses CBC, so refuse
it with an AEAD cipher rather than allocate 64 AEAD transforms. The
check cannot go in crypt_iv_lmk_ctr with the other lmk checks, because
the IV constructor runs after crypt_set_key.

Note that this is not a security bug because the memory corruption can
only be triggered by root.

## Which versions are affected by CVE-2026-99037?


## How do I fix CVE-2026-99037?

Upgrade to a fixed version.

## Is CVE-2026-99037 being exploited?

There is no known exploitation of CVE-2026-99037 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-99037 and fix it if it is affected.

What it is: CVE-2026-99037 is a vulnerability in Linux, published on 23 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-99037 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-2026-99037/ (Markdown: https://insights.sbomify.com/CVE-2026-99037/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-99037
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-99037
- OSV: https://osv.dev/vulnerability/CVE-2026-99037

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-99037/
Summaries are generated and may contain mistakes; the official description above is the record.