UBUNTU-CVE-2025-49600

See a problem?
Please try reporting it to the source first.

Source

https://ubuntu.com/security/CVE-2025-49600

Import Source

https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2025/UBUNTU-CVE-2025-49600.json

JSON Data

https://api.osv.dev/v1/vulns/UBUNTU-CVE-2025-49600

Upstream

CVE-2025-49600

Published

2025-07-04T15:15:00Z

Modified

2026-05-20T16:23:32Z

Severity

4.9 (Medium) CVSS_V3 - CVSS:3.1/AV:P/AC:H/PR:N/UI:N/S:C/C:N/I:H/A:N CVSS Calculator
Ubuntu - medium

Summary

[none]

Details

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.

References

Affected packages

Ubuntu:25.10 / mbedtls

Package

Name: mbedtls
Purl: pkg:deb/ubuntu/mbedtls?arch=source&distro=questing

Affected ranges

Type: ECOSYSTEM
Events: Introduced

0 Unknown introduced version / All previous versions are affected

Affected versions

3.*

3.6.2-3ubuntu1

Ecosystem specific

{
    "binaries": [
        {
            "binary_name": "libmbedcrypto16",
            "binary_version": "3.6.2-3ubuntu1"
        },
        {
            "binary_name": "libmbedtls21",
            "binary_version": "3.6.2-3ubuntu1"
        },
        {
            "binary_name": "libmbedx509-7",
            "binary_version": "3.6.2-3ubuntu1"
        }
    ]
}

Database specific

source

"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2025/UBUNTU-CVE-2025-49600.json"

Ubuntu:26.04:LTS / mbedtls