CVE-2025-49600 Security feature bypass in mbedtls
Attackers can bypass LMS signature verification in MbedTLS by inducing hardware hash accelerator faults, leading to acceptance of invalid signatures.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-49600?
CVE-2025-49600 is a medium-severity vulnerability in mbedtls, published on 4 Jul 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Official 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.
Weakness: CWE-325
Which versions are affected by CVE-2025-49600?
It affects 1 product.
Products include Trustedfirmware Mbed Tls.
How do I fix CVE-2025-49600?
Upgrade to a fixed version.
Is CVE-2025-49600 being exploited?
There is no known exploitation of CVE-2025-49600 in the wild and no public exploit code.
Other vulnerabilities in mbedtls
Sources
Also known as ALPINE-CVE-2025-49600, DEBIAN-CVE-2025-49600, GHSA-r3gf-c2cf-vp8q, UBUNTU-CVE-2025-49600.