CVE-2025-66442

low-risk
Published 2026-04-01

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.

Do I need to act?

-
0.02% chance of exploitation
EPSS score — low exploit probability
-
Not on CISA KEV list
No confirmed active exploitation reported to CISA
?
Patch status unknown
Check vendor advisories for fix availability and mitigation guidance
5
CVSS 5.1/10 Medium
LOCAL / HIGH complexity

Affected Products (2)

Tf-Psa-Crypto

Affected Vendors

Arm

References (4)

Release Notes https://github.com/Mbed-TLS/TF-PSA-Crypto/releases
Release Notes https://github.com/Mbed-TLS/mbedtls/releases
Vendor Advisory https://mbed-tls.readthedocs.io/en/latest/security-advisories/
Vendor Advisory https://mbed-tls.readthedocs.io/en/latest/security-advisories/mbedtls-security-a...
20
/ 100
low-risk
Severity 13/34 · Low
Exploitability 0/34 · Minimal
Exposure 7/34 · Low