6.5

CVE-2026-25834: trustedfirmware mbed_tls Improper Certificate Validation

CVSS: 6.5v3.1MediumAnalyzed
AliasesALPINE-CVE-2026-25834UBUNTU-CVE-2026-25834DEBIAN-CVE-2026-25834
Published 01-04-2026Last modified 01-04-2026
Open JSON

Vulnerability summary

CVE-2026-25834 is a medium (CVSS 6.5) Improper Certificate Validation vulnerability in trustedfirmware mbed_tls. EPSS estimates a 0.22% chance of exploitation in the next 30 days, higher than 11.4% of scored vulnerabilities.

Overall risk
26/100
0100
Medium · default modelHow is this calculated?
CVSS score
6.5/10
010
Medium · v3.1 (CVE.org)
EPSS score
0.22%
0%100%
Low · +0.08 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 3 · Related 3
OPENSUSE-SU-2026:10498-1OPENSUSE-SU-2026:21144-1SUSE-SU-2026:22016-1

Timeline

  1. 01-04-2026
    PublishedVulnerability first disclosed.
  2. 01-04-2026
    Last modifiedVulnerability information updated.

Description

Mbed TLS v3.3.0 up to 3.6.5 and 4.0.0 allows Algorithm Downgrade.

CVSS metrics

5 scores · 5 sources · 1 version

EPSS trend

Probability

0.22%

Chance of exploitation in the next 30 days

Percentile

11%

Versus all other CVEs

30-day change

+0.08 pp

From 0.14% on 20-09-2026

20-09-202620-10-2026
EPSS score
0.22%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Alpine1 product
  • mbedtls< 3.6.6-r0
Debian1 product
  • mbedtls< 3.6.6-0.1~deb13u1 | < 3.6.6-0.1
Trustedfirmware1 product
Ubuntu1 product
  • mbedtlsAll versions (No fix recorded)

4 vendors · 4 products

References

6 links