---
title: "CVE-2025-49600\n    | Ubuntu"
description: Ubuntu is an open source software operating system that runs from the
  desktop, to the cloud, to all your internet connected things.
url: https://ubuntu.com/security/CVE-2025-49600?format=md
keywords: index, follow
---

# CVE-2025-49600

Publication date 4 July 2025

Last updated 8 October 2025

---

Ubuntu priority

**Medium**

[Why this priority?](https://ubuntu.com/security/cves/about#priority )

## Cvss 3 Severity Score

**4.9 · Medium**

[Score breakdown](https://ubuntu.com/security/CVE-2025-49600?format=md#impact-score)

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## 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.

[Read the notes from the security team](https://ubuntu.com/security/CVE-2025-49600?format=md#notes)

## Status

Show unmaintained releases

| Package | Ubuntu Release | Status |
| --- | --- | --- |
| mbedtls | 26.04 LTS resolute | Vulnerable |
| 25.10 questing | Ignored end of life, was needed |
| 25.04 plucky | Ignored end of life, was needed |
| 24.10 oracular | Ignored end of life, was needs-triage |
| 24.04 LTS noble | Not affected |
| 22.04 LTS jammy | Not affected |
| 20.04 LTS focal | Not affected |
| 18.04 LTS bionic | Not affected |
| 16.04 LTS xenial | Not affected |

---

* [How can I get the fixes?](https://ubuntu.com/security/cves/about#security)
* [What do statuses mean?](https://ubuntu.com/security/cves/about#statuses)

## Notes

---

### [hlibk](https://launchpad.net/~hlibk)

Versions below 3.3.0 are not affected

## Severity score breakdown

CVSS version:
CVSS v3.0

**Base score**

4.9 · Medium

* Base metrics

  | Parameter | Value |
  | --- | --- |
  | Attack vector | Physical |
  | Attack complexity | High |
  | Privileges required | None |
  | User interaction | None |
  | Scope | Changed |
  | Confidentiality impact | None |
  | Integrity impact | High |
  | Availability impact | None |
* Scores

  | Parameter | Value |
  | --- | --- |
  | Base score | 4.9 · Medium |
  | Exploitability score | - |
  | Impact score | - |

**Vector:** CVSS:3.1/AV:P/AC:H/PR:N/UI:N/S:C/C:N/I:H/A:N

## References

* [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2025-49600)
* [NVD](https://nvd.nist.gov/vuln/detail/CVE-2025-49600)
* [Launchpad](https://launchpad.net/bugs/cve/CVE-2025-49600)
* [Debian](https://security-tracker.debian.org/tracker/CVE-2025-49600)

### Other references

* <https://www.cve.org/CVERecord?id=CVE-2025-49600>
* <https://github.com/Mbed-TLS/mbedtls-docs/blob/main/security-advisories/mbedtls-security-advisory-2025-06-3.md>