# CVE-2025-27810: Security feature bypass in mbedtls

> Attackers can bypass TLS authentication and perform replays due to uninitialized memory usage in Mbed TLS during specific error conditions.

- **Severity:** Medium 5.4 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 25 Mar 2025
- **Updated:** 25 Mar 2025
- **Also known as:** ALPINE-CVE-2025-27810, DEBIAN-CVE-2025-27810, GHSA-vvqm-mmw4-qwg5, JLSEC-2025-187, ROOT-OS-DEBIAN-12-CVE-2025-27810, UBUNTU-CVE-2025-27810

## What is CVE-2025-27810?

CVE-2025-27810 is a medium-severity vulnerability in Arm Mbed Tls, published on 25 Mar 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Mbed TLS before 2.28.10 and 3.x before 3.6.3, in some cases of failed memory allocation or hardware errors, uses uninitialized stack memory to compose the TLS Finished message, potentially leading to authentication bypasses such as replays.

Weakness: CWE-908 (Use of Uninitialized Resource)

## Which versions are affected by CVE-2025-27810?

It affects 2 products.


Products: Arm Mbed Tls, Trustedfirmware Mbed Tls.

## How do I fix CVE-2025-27810?

Upgrade to a fixed version.

## Is CVE-2025-27810 being exploited?

There is no known exploitation of CVE-2025-27810 in the wild and no public exploit code.

## 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-2025-27810 and fix it if it is affected.

What it is: CVE-2025-27810 is a medium-severity vulnerability in Arm Mbed Tls, published on 25 Mar 2025. 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-2025-27810 in the wild and no public exploit code.

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-2025-27810/ (Markdown: https://insights.sbomify.com/CVE-2025-27810/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-27810
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-27810
- OSV: https://osv.dev/vulnerability/CVE-2025-27810

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-27810/
Summaries are generated and may contain mistakes; the official description above is the record.