VulnerabilityAnalyzed
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.
MEDIUM 5.1EPSS 0.27%
Does this matter?
Lower severity and a low EPSS score (0.27%). Track it; it rarely justifies an emergency change on its own.
Description
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.
- CVSS 3.1
- 5.1 MEDIUMCVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
- EPSS
- 0.27% probability · 19th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-385
- Affected
- arm/mbed tls · arm/tf-psa-crypto
- Source
- cve@mitre.org
References
- https://github.com/Mbed-TLS/TF-PSA-Crypto/releasesRelease Notes
- https://github.com/Mbed-TLS/mbedtls/releasesRelease Notes
- https://mbed-tls.readthedocs.io/en/latest/security-advisories/Vendor Advisory
- https://mbed-tls.readthedocs.io/en/latest/security-advisories/mbedtls-security-advisory-2026-03-compiler-induced-constant-time-violations/Vendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.