CVE-2026-25834
Published: 01 April 2026
Summary
CVE-2026-25834 is a medium-severity Improper Certificate Validation (CWE-295) vulnerability in Trustedfirmware Mbed Tls. Its CVSS base score is 6.5 (Medium).
Operationally, exploitation aligns with the MITRE ATT&CK technique Downgrade Attack (T1689); ranked at the 3.3th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-17967
Vulnerability details
Mbed TLS v3.3.0 up to 3.6.5 and 4.0.0 allows Algorithm Downgrade.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Direct match to algorithm downgrade weakness enabling T1562.010.
Affected Assets
Mitigating Controls
Likely Mitigating Controls AI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Contacts with security groups provide timely information on broken or risky cryptographic algorithms, reducing the likelihood of their selection and use.
Ongoing education and sharing of recommended practices helps organizations identify and migrate away from broken or risky cryptographic algorithms.
Cross-organization threat feeds commonly include advances in cryptanalysis and active exploits against weak or broken algorithms, allowing organizations to deprecate them proactively.
Capital planning and funding allow selection and ongoing support of strong cryptographic algorithms rather than weak or broken ones.
Risk updates surface newly-broken or risky cryptographic algorithms as threat intelligence and computing advances evolve, enabling timely replacement.
Scanners flag use of broken or weak cryptographic algorithms via known-vulnerability databases.
When certificates are used to establish component provenance, the control requires correct certificate validation procedures.
Enforces approved cryptographic algorithms for each use case, blocking use of broken or risky algorithms.