CVE-2025-49600 - MbedTLS LMS Signature Forgery Vulnerability

CVE-2025-49600 - MbedTLS LMS Signature Forgery Vulnerability

https://cvefeed.io/rssfeed/latest.atom / Fri, 07/04/2025 - 20:28
CVE ID : CVE-2025-49600
Published : July 4, 2025, 3:15 p.m. | 2 hours, 54 minutes ago
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.
Severity: 4.9 | MEDIUM
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