Status: UPDATED | Advisory ID: CVE-2026-66402
| CVE | CVE-2026-66402 |
| CVSS Score / Version | 9.8 (Critical) / CVSS v3.1 |
| Updated | 2026-10-02 |
| CVSS Vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| CVSS Prose | attack vector is network; attack complexity is low; privileges required is none; user interaction is none; scope is unchanged; confidentiality impact is high; integrity impact is high; availability impact is high. |
| Affected products | freerdp freerdp |
| Classified as | CWE-295 (Improper Certificate Validation) |
| Vendor | Product | Affected Versions | Patch Status |
|---|---|---|---|
| freerdp | freerdp |
| Subsystems | General OT |
| Sectors | Multiple |
FreeRDP before 3.29.0 (affected versions <= 3.28.0) contains multiple TLS certificate identity validation weaknesses in tls_verify_certificate(), tls_match_hostname(), and x509_utils_get_dns_names(). Because FreeRDP performs custom Common Name and DNS SAN string matching instead of using OpenSSL's length-aware identity validation APIs, it (1) truncates DNS SAN values at embedded NUL bytes (accepting e.g. 'victim.example\0.attacker.example' as 'victim.example'), (2) accepts a matching Common Name even when non-matching DNS SAN entries are present, and (3) accepts IP-literal targets via DNS/CN matching without comparing iPAddress SANs. Under a trusted or misissued certificate chain, an attacker positioned to present such a certificate can bypass server identity verification, weakening TLS server authentication. (NVD)
Monitor freerdp's web page for any future patch releases. See vendor advisory link below.