CVE intelligence

CVE-2025-66442

Vulnerability intelligence

Published Apr 1, 2026Sources checked Sep 27, 2026

5.1MEDIUMCVSS out of 10

What this means

Review the available evidence

CVE-2025-66442 and is rated Medium severity with a CVSS score of 5.1. It is not in the current CISA KEV record we collected. That does not prove exploitation has not occurred.

CISA KEVNot listedBased on the latest collected catalog

EPSS0.3%Estimated 30-day exploitation probability

Ransomware useNot markedCISA KEV ransomware field

Threat actors0Source-linked actor relationships

Overview

What is CVE-2025-66442?

In Mbed TLS through 4.0.0, there is a compiler-induced timing side channel (in RSA and CBC/ECB decryption) that only occurs with LLVM's select-optimize feature. TF-PSA-Crypto through 1.0.0 is also affected.