The flaw exists in Mbed TLS versions 3.3.0 through 3.6.5 and 4.0.0, enabling an attacker to force the library to use a weaker cryptographic algorithm. The downgrade bypasses expected security parameters, potentially allowing cryptographic keys to be derived in an unsuitable form or breaking data integrity. The associated Common Weakness identifiers highlight improper certificate validation, use of risky algorithms, and selection of weak cryptographic primitives.

ARM’s Mbed TLS library, widely deployed in embedded and IoT devices, is affected. The vulnerability spans releases 3.3.0 up to 3.6.5 and the 4.0.0 major line. Systems relying on these versions—including embedded firmware, network appliances, and connected sensors—must assess whether the vulnerable library is in use.

With a CVSS base score of 6.5 the issue is considered moderate severity; however, exploitation likelihood is low according to the EPSS metric (<1%) and the vulnerability is not currently listed in the CISA KEV catalog. Successful exploitation would require the attacker to supply crafted algorithm identifiers, which suggests a remote configuration or protocol‑level vector, though precise conditions are not detailed in the advisory. Vulnerable deployments lacking updated cryptographic material thus face risk of weakened encryption or authentication.