# CVE-2025-49600: Security feature bypass in mbedtls

> Attackers can bypass LMS signature verification in MbedTLS by inducing hardware hash accelerator faults, leading to acceptance of invalid signatures.

- **Severity:** Medium 4.9 (`CVSS:3.1/AV:P/AC:H/PR:N/UI:N/S:C/C:N/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:** 8 Jul 2025
- **Also known as:** ALPINE-CVE-2025-49600, DEBIAN-CVE-2025-49600, GHSA-r3gf-c2cf-vp8q, UBUNTU-CVE-2025-49600

## What is CVE-2025-49600?

CVE-2025-49600 is a medium-severity vulnerability in mbedtls, 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

In MbedTLS 3.3.0 before 3.6.4, mbedtls_lms_verify may accept invalid signatures if hash computation fails and internal errors go unchecked, enabling LMS (Leighton-Micali Signature) forgery in a fault scenario. Specifically, unchecked return values in mbedtls_lms_verify allow an attacker (who can induce a hardware hash accelerator fault) to bypass LMS signature verification by reusing stale stack data, resulting in acceptance of an invalid signature. In mbedtls_lms_verify, the return values of the internal Merkle tree functions create_merkle_leaf_value and create_merkle_internal_value are not checked. These functions return an integer that indicates whether the call succeeded or not. If a failure occurs, the output buffer (Tc_candidate_root_node) may remain uninitialized, and the result of the signature verification is unpredictable. When the software implementation of SHA-256 is used, these functions will not fail. However, with hardware-accelerated hashing, an attacker could use fault injection against the accelerator to bypass verification.

Weakness: CWE-325 (Missing Cryptographic Step)

## Which versions are affected by CVE-2025-49600?

It affects 1 product.


Products: Trustedfirmware Mbed Tls.

## How do I fix CVE-2025-49600?

Upgrade to a fixed version.

## Is CVE-2025-49600 being exploited?

There is no known exploitation of CVE-2025-49600 in the wild and no public exploit code.

## Other vulnerabilities in mbedtls

- [CVE-2026-34875](https://insights.sbomify.com/CVE-2026-34875/): Memory corruption in n/a (critical 9.8)
- [CVE-2024-49195](https://insights.sbomify.com/CVE-2024-49195/): Memory corruption in n/a (critical 9.8)
- [CVE-2024-45158](https://insights.sbomify.com/CVE-2024-45158/): Memory corruption in n/a (critical 9.8)
- [CVE-2024-45159](https://insights.sbomify.com/CVE-2024-45159/): Auth bypass in n/a (critical 9.8)
- [CVE-2023-45199](https://insights.sbomify.com/CVE-2023-45199/): Mbed TLS 3.2.x through 3.4.x before 3.5 has a Buffer Overflow that can lead to remote Code execution. (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-49600 and fix it if it is affected.

What it is: CVE-2025-49600 is a medium-severity vulnerability in mbedtls, published on 4 Jul 2025. 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-2025-49600 in the wild and no public exploit code.

Affected product: mbedtls. 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-2025-49600/ (Markdown: https://insights.sbomify.com/CVE-2025-49600/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-49600
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-49600
- OSV: https://osv.dev/vulnerability/CVE-2025-49600

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-49600/
Summaries are generated and may contain mistakes; the official description above is the record.