What’s Vulnerable › Vulnerabilities
CVE-2025-49600
- Severity: medium (CVSS 4.9 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 0.2% probability of exploitation in the next 30 days
- Public exploit or detection template: none known
- Published: 2025-07-04 · updated 2026-06-17
- Weakness: CWE-325
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.
Affected products
- TrustedFirmware Mbed TLS: from 3.3.0 before 3.6.4 — fixed in 3.6.4
How to fix
Upgrade to a fixed version: TrustedFirmware Mbed TLS 3.6.4. Check the vendor advisory for mitigations.
References
Get alerted when CVE-2025-49600 or the next vulnerability affects your stack