CVE-2025-66442
Arm Mbed Tls ≤ 4.0.0
Raw vector
CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:NSummary
CVE-2025-66442 is a medium-severity Covert Timing Channel (CWE-385) vulnerability in Arm Mbed Tls. Its CVSS base score is 5.1 (Medium).
Operationally, exploitation aligns with the MITRE ATT&CK technique Data Obfuscation (T1001); ranked at the 19th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to SC-31 (Covert Channel Analysis) — see the control section below for these in your framework.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2025-209171
Vulnerability Data
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.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Covert channel analysis directly identifies timing channels that could leak information.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Secure development practices (reviews, testing) directly reduce introduction of timing-channel vulnerabilities in code.
Runtime monitoring of hardware/software behavior can detect anomalous timing patterns that indicate covert channels.
Vulnerability identification processes can surface timing-channel weaknesses during design or code analysis.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Detailed logging can reveal timing anomalies but does not prevent covert timing channels.
Continuous monitoring may detect timing-based exfiltration but does not eliminate the channel itself.
Network segmentation reduces attack surface but does not address intra-process timing channels.
Network segregation limits external timing observation but not internal covert timing.
Secure architecture principles can include timing-channel countermeasures but are not specific.
Secure coding guidelines may recommend constant-time algorithms but coverage is not guaranteed.