# CVE-2021-44538: Memory corruption in n/a

> A buffer overflow in libolm allows remote attackers to potentially execute code or cause denial of service via crafted messages.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 14 Dec 2021
- **Updated:** 4 Aug 2024
- **Also known as:** DEBIAN-CVE-2021-44538, GHSA-q7f4-j236-f4hc, MGASA-2021-0571, UBUNTU-CVE-2021-44538

## What is CVE-2021-44538?

CVE-2021-44538 is a critical memory corruption vulnerability in Debian Debian Linux, published on 14 Dec 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The olm_session_describe function in Matrix libolm before 3.2.7 is vulnerable to a buffer overflow. The Olm session object represents a cryptographic channel between two parties. Therefore, its state is partially controllable by the remote party of the channel. Attackers can construct a crafted sequence of messages to manipulate the state of the receiver's session in such a way that, for some buffer sizes, a buffer overflow happens on a call to olm_session_describe. Furthermore, safe buffer sizes were undocumented. The overflow content is partially controllable by the attacker and limited to ASCII spaces and digits. The known affected products are Element Web And SchildiChat Web.

Weakness: CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer)

## Which versions are affected by CVE-2021-44538?

It affects 6 products.


Products: Cinny Project Cinny, Debian Debian Linux, Matrix Element, Matrix Javascript Sdk, Matrix Olm, Schildi Schildichat.

## How do I fix CVE-2021-44538?

Upgrade to a fixed version.

## Is CVE-2021-44538 being exploited?

There is no known exploitation of CVE-2021-44538 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-44538 and fix it if it is affected.

What it is: CVE-2021-44538 is a critical memory corruption vulnerability in Debian Debian Linux, published on 14 Dec 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-44538 in the wild and no public exploit code.

Affected product: Debian Debian 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-2021-44538/ (Markdown: https://insights.sbomify.com/CVE-2021-44538/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-44538
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-44538
- OSV: https://osv.dev/vulnerability/CVE-2021-44538

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-44538/
Summaries are generated and may contain mistakes; the official description above is the record.