CVE-2025-49600

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.

How to fix CVE-2025-49600

To remediate CVE-2025-49600, upgrade the affected package to a fixed version below.

• —upgrade to 3.6.4-r0 or later
• —upgrade to 3.6.4-1 or later

Is CVE-2025-49600 being exploited?

Low — EPSS is 0.0%, meaning exploitation activity has not been observed at scale.

Affected packages (2)

• from 0, < 3.6.4-r0
• from 0, < 3.6.4-1

CVSS scores

References (2)

• ADVISORYsecurity.alpinelinux.org/vuln/CVE-2025-49600
• ADVISORYsecurity-tracker.debian.org/tracker/CVE-2025-49600