Vulnerability · Published Apr 1, 2026 · Assigned by mitre
CVE-2025-66442
Medium 5.1
In plain English
A medium-severity security flaw in the mbedtls package (Debian). There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 21% of all known vulnerabilities).
Severity (CVSS 3.1)5.1Medium
Exploit odds (30 days)0.3%top 79.4% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | mbedtls | no fix listed | DEBIAN-CVE-2025-66442 |
| Debian:13 | mbedtls | no fix listed | DEBIAN-CVE-2025-66442 |
| Debian:14 | mbedtls | no fix listed | DEBIAN-CVE-2025-66442 |
| Ubuntu:25.10 | mbedtls | no fix listed | UBUNTU-CVE-2025-66442 |
| Ubuntu:26.04:LTS | mbedtls | no fix listed | UBUNTU-CVE-2025-66442 |
| Ubuntu:26.10 | mbedtls | no fix listed | UBUNTU-CVE-2025-66442 |
Affected products (as reported)
Weakness: CWE-385 · Vector: CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N