CVE-2025-66442
Publication date 1 April 2026
Last updated 13 April 2026
Ubuntu priority
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.
Status
| Package | Ubuntu Release | Status |
|---|---|---|
| mbedtls | 25.10 questing |
Vulnerable, fix deferred
|
| 24.04 LTS noble |
Vulnerable, fix deferred
|
|
| 22.04 LTS jammy |
Vulnerable, fix deferred
|
|
| 20.04 LTS focal |
Vulnerable, fix deferred
|
|
| 18.04 LTS bionic |
Vulnerable, fix deferred
|
|
| 16.04 LTS xenial |
Vulnerable, fix deferred
|
Notes
Severity score breakdown
| Parameter | Value |
|---|---|
| Base score |
5.1 · Medium
|
| Attack vector | Local |
| Attack complexity | High |
| Privileges required | None |
| User interaction | None |
| Scope | Unchanged |
| Confidentiality | High |
| Integrity impact | None |
| Availability impact | None |
| Vector | CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N |
References
Other references
- https://www.cve.org/CVERecord?id=CVE-2025-66442
- https://github.com/Mbed-TLS/TF-PSA-Crypto/releases
- https://github.com/Mbed-TLS/mbedtls/releases
- https://mbed-tls.readthedocs.io/en/latest/security-advisories/
- https://mbed-tls.readthedocs.io/en/latest/security-advisories/mbedtls-security-advisory-2026-03-compiler-induced-constant-time-violations/