CVE-2026-25834 Details
Description
Mbed TLS v3.3.0 up to 3.6.5 and 4.0.0 allows Algorithm Downgrade.
A vulnerability allowing algorithm downgrade in signature processing has been identified in Mbed TLS versions 3.3.0 prior to 3.6.5 and 4.0.0. This issue arises because the Mbed TLS client in these versions accepts any signature algorithm choice made by the server for TLS 1.2, disregarding the client's configured security policy. As a result, a server could potentially force a client to accept a less secure algorithm, bypassing the client's intended security settings.
Users are advised to upgrade to Mbed TLS versions 3.6.6 or 4.1.0. For those maintaining branches with backported bug fixes, relevant commits are available for Mbed TLS 3.6.x and Mbed TLS 4.x.
Metrics
CVSS 4.0 Severity and Vector Strings:
No CVSS 4.0 data is available for this CVE.
CVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
CISA-ADP
Assessed Apr 1, 2026References to Advisories, Solutions, and Tools
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Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-295 | Improper Certificate Validation | CISA-ADP |
| CWE-327 | Use of a Broken or Risky Cryptographic Algorithm | CISA-ADP |
Affected Products
| Product | Versions |
|---|---|
| trustedfirmware mbed tls | >= 3.3.0, < 3.6.6 4.0.0 |
CPE
Remediation
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Change History
7 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jun 17, 2026 | CVE Modified | [email protected] |
| Jun 17, 2026 | CVE Modified | CISA-ADP |
| Jun 5, 2026 | CPE Deprecation Remap | [email protected] |
| Jun 5, 2026 | CPE Deprecation Remap | [email protected] |
| Apr 6, 2026 | Initial Analysis | [email protected] |
| Apr 1, 2026 | CVE Modified | CISA-ADP |
| Apr 1, 2026 | New CVE Received | [email protected] |