Vulnerability 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.
CVSS Score
MEDIUM
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Arm | Mbed Tls | >= 3.3.0, < 3.6.4 |
Related Weaknesses (CWE)
References
- https://github.com/Mbed-TLS/mbedtls-docs/blob/main/security-advisories/mbedtls-sThird Party Advisory
FAQ
What is CVE-2025-49600?
CVE-2025-49600 is a vulnerability with a CVSS score of 4.9 (MEDIUM). 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 ...
How severe is CVE-2025-49600?
CVE-2025-49600 has been rated MEDIUM with a CVSS base score of 4.9/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2025-49600?
Check the references section above for vendor advisories and patch information. Affected products include: Arm Mbed Tls.