Vulnerability · Published Apr 1, 2026 · Assigned by mitre
CVE-2026-25834
Medium 6.5
In plain English
A medium-severity improper certificate validation in the mbedtls package (Alpine). There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.1% (higher than 3% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS 3.1)6.5Medium
Exploit odds (30 days)0.1%top 96.6% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
Mbed TLS v3.3.0 up to 3.6.5 and 4.0.0 allows Algorithm Downgrade.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine:v3.20 | mbedtls | 3.6.6-r0 | ALPINE-CVE-2026-25834 |
| Alpine:v3.21 | mbedtls | 3.6.6-r0 | ALPINE-CVE-2026-25834 |
| Alpine:v3.22 | mbedtls | 3.6.6-r0 | ALPINE-CVE-2026-25834 |
| Alpine:v3.23 | mbedtls | 3.6.6-r0 | ALPINE-CVE-2026-25834 |
| Alpine:v3.24 | mbedtls | 3.6.6-r0 | ALPINE-CVE-2026-25834 |
| Alpine:v3.24 | mbedtls3 | 3.6.6-r0 | ALPINE-CVE-2026-25834 |
| Debian:13 | mbedtls | 3.6.6-0.1~deb13u1 | DEBIAN-CVE-2026-25834 |
| Debian:14 | mbedtls | 3.6.6-0.1 | DEBIAN-CVE-2026-25834 |
| Ubuntu:25.10 | mbedtls | no fix listed | UBUNTU-CVE-2026-25834 |
| Ubuntu:26.04:LTS | mbedtls | no fix listed | UBUNTU-CVE-2026-25834 |
| Ubuntu:26.10 | mbedtls | no fix listed | UBUNTU-CVE-2026-25834 |
Affected products (as reported)
Weakness: CWE-295, CWE-327 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L