# CVE-2025-52496: Race condition in mbedtls

> A race condition in Mbed TLS allows attackers to extract AES keys or forge GCM tags in multithreaded applications.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 4 Jul 2025
- **Updated:** 3 Nov 2025
- **Also known as:** ALPINE-CVE-2025-52496, DEBIAN-CVE-2025-52496, GHSA-qc26-g9mm-wmmf, JLSEC-2025-228, ROOT-OS-DEBIAN-12-CVE-2025-52496, UBUNTU-CVE-2025-52496

## What is CVE-2025-52496?

CVE-2025-52496 is a high-severity vulnerability in Arm Mbed Tls, published on 4 Jul 2025. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

Mbed TLS before 3.6.4 has a race condition in AESNI detection if certain compiler optimizations occur. An attacker may be able to extract an AES key from a multithreaded program, or perform a GCM forgery.

Weakness: CWE-733 (Compiler Optimization Removal or Modification of Security-critical Code)

## Which versions are affected by CVE-2025-52496?

It affects 1 product.


Products: Arm Mbed Tls.

## How do I fix CVE-2025-52496?

Upgrade to a fixed version.

## Is CVE-2025-52496 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-52496 exists.

## Other vulnerabilities in Arm Mbed Tls

- [CVE-2026-34877](https://insights.sbomify.com/CVE-2026-34877/): Deserialization in n/a (critical 9.8)
- [CVE-2022-46393](https://insights.sbomify.com/CVE-2022-46393/): Memory corruption in n/a (critical 9.8)
- [CVE-2021-44732](https://insights.sbomify.com/CVE-2021-44732/): Use after free in n/a (critical 9.8)
- [CVE-2017-18187](https://insights.sbomify.com/CVE-2017-18187/): Integer overflow in n/a (critical 9.8)
- [CVE-2018-0487](https://insights.sbomify.com/CVE-2018-0487/): Memory corruption in ARM mbed TLS before 1.3.22, before 2.1.10, and before 2.7.0 (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-52496 and fix it if it is affected.

What it is: CVE-2025-52496 is a high-severity vulnerability in Arm Mbed Tls, published on 4 Jul 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-52496 exists.

Affected product: Arm Mbed Tls. 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-2025-52496/ (Markdown: https://insights.sbomify.com/CVE-2025-52496/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-52496
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-52496
- OSV: https://osv.dev/vulnerability/CVE-2025-52496

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-52496/
Summaries are generated and may contain mistakes; the official description above is the record.