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Vulnerability record · CVE-2025-66442 · published 1 April 2026

CVE-2025-66442: Arm mbed tls vulnerability

Arm · Mbed Tls

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.

5.1 CVSS 3.1 Medium EPSS 0.27% · top 82.5% CWE-385 · CWE-385
5.1CVSS 3.1 base score
0.27%EPSS exploitation probability, 30 days
NoNot in CISA KEV
2Affected product versions listed by NVD
4References
17 Jun 2026Last modified by NVD

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/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

Affected products

2 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/Mbed-TLS/TF-PSA-Crypto/releases Release Notes
https://github.com/Mbed-TLS/mbedtls/releases Release 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-constan Vendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2025-66442), CISA KEV, FIRST EPSS (scores of 2026-10-03). This page is refreshed as NVD updates the record.