Is CVE-2025-49600 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2025-49600 being exploited in the wild.

How severe is CVE-2025-49600?

Medium severity, with a CVSS score of 4.9, published 4 July 2025.

Which products and versions are affected?

TrustedFirmware Mbed TLS 3.3.0 to 3.6.3.

Is there a fix for CVE-2025-49600?

No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

How is CVE-2025-49600 attacked?

It is attacked with physical access, in a software library.

Am I affected by CVE-2025-49600?

Check whether anything you run is named in the advisory. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2025-49600: Mbed TLS signature bypass in LMS verification

CVE-2025-49600 · Severity: medium · CVSS 4.9 · Published 2025-07-04

Mbed TLS is a widely used library that provides cryptographic and SSL/TLS capabilities for embedded devices. A vulnerability in its signature verification process could allow an attacker with physical access to the device to bypass security checks. By interfering with the device's hardware during a calculation, an attacker could trick the system into accepting a forged digital signature, potentially allowing unauthorized software or commands to be executed.

Quick answers

Is CVE-2025-49600 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2025-49600 being exploited in the wild.
How severe is CVE-2025-49600?: Medium severity, with a CVSS score of 4.9, published 4 July 2025.
Which products and versions are affected?: TrustedFirmware Mbed TLS 3.3.0 to 3.6.3.
Is there a fix for CVE-2025-49600?: No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2025-49600 attacked?: It is attacked with physical access, in a software library.
Am I affected by CVE-2025-49600?: Check whether anything you run is named in the advisory. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

A vulnerability exists in the mbedtls_lms_verify() function due to unchecked return values from internal Merkle tree functions, specifically create_merkle_leaf_value() and create_merkle_internal_value(). When hardware-accelerated hashing is used, an attacker can use physical fault injection to cause these functions to fail. Because the return values are not validated, the output buffer (Tc_candidate_root_node) may remain uninitialized or contain stale data from a previous successful verification. This allows an attacker to bypass signature verification by reusing valid root node data remaining on the stack. The issue is resolved in Mbed TLS 3.6.4.

Affected products

TrustedFirmware Mbed TLS 3.3.0 to 3.6.3

Timeline

2025-06-30: advisory: Original security advisory date
2025-07-04: disclosed: NVD publication date

References

https://github.com/Mbed-TLS/mbedtls-docs/blob/main/security-advisories/mbedtls-security-advisory-2025-06-3.md

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