FreeRDP before 3.29.0 improperly validates the Extended Key Usage (EKU) purpose of the peer certificate during client-side server TLS authentication. (CVE-2026-67294)
FreeRDP before 3.29.0 improperly validates the Extended Key Usage (EKU) purpose of the peer certificate during client-side server TLS authentication. In x509_utils_verify(), when server-purpose (X509_PURPOSE_SSL_SERVER) verification fails, the code falls back to client-purpose and any-purpose verification, so a trusted, hostname-matching certificate valid only for clientAuth can be accepted as the RDP server certificate. In environments relying on EKU separation between client and server certificates, this allows a clientAuth-only certificate issued by a trusted CA to bypass server certificate purpose validation.
AI Analysis
Technical Summary
The vulnerability in FreeRDP prior to version 3.29.0 involves improper validation of the Extended Key Usage (EKU) purpose in peer certificates during TLS authentication on the client side. Specifically, in the x509_utils_verify() function, if the server-purpose EKU check (X509_PURPOSE_SSL_SERVER) fails, the code incorrectly falls back to verifying client-purpose and any-purpose EKUs. This flaw allows a trusted certificate valid only for client authentication (clientAuth) to be accepted as a valid RDP server certificate, undermining the intended separation of client and server certificate purposes in environments that rely on EKU distinctions.
Potential Impact
An attacker with a clientAuth-only certificate issued by a trusted CA could bypass server certificate purpose validation and impersonate an RDP server. This could lead to clients accepting malicious servers, resulting in potential confidentiality breaches. The vulnerability does not affect integrity or availability directly but compromises the trust model of TLS authentication in FreeRDP.
Mitigation Recommendations
No official patch or fix is currently confirmed for this vulnerability. Users should monitor the FreeRDP vendor advisories for updates and apply official fixes once available. Until then, environments relying on strict EKU separation should consider additional network-level controls or certificate validation mechanisms to mitigate risk.
FreeRDP before 3.29.0 improperly validates the Extended Key Usage (EKU) purpose of the peer certificate during client-side server TLS authentication. (CVE-2026-67294)
Description
FreeRDP before 3.29.0 improperly validates the Extended Key Usage (EKU) purpose of the peer certificate during client-side server TLS authentication. In x509_utils_verify(), when server-purpose (X509_PURPOSE_SSL_SERVER) verification fails, the code falls back to client-purpose and any-purpose verification, so a trusted, hostname-matching certificate valid only for clientAuth can be accepted as the RDP server certificate. In environments relying on EKU separation between client and server certificates, this allows a clientAuth-only certificate issued by a trusted CA to bypass server certificate purpose validation.
CVSS v3.1
Score 5.9medium
Affected software
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability in FreeRDP prior to version 3.29.0 involves improper validation of the Extended Key Usage (EKU) purpose in peer certificates during TLS authentication on the client side. Specifically, in the x509_utils_verify() function, if the server-purpose EKU check (X509_PURPOSE_SSL_SERVER) fails, the code incorrectly falls back to verifying client-purpose and any-purpose EKUs. This flaw allows a trusted certificate valid only for client authentication (clientAuth) to be accepted as a valid RDP server certificate, undermining the intended separation of client and server certificate purposes in environments that rely on EKU distinctions.
Potential Impact
An attacker with a clientAuth-only certificate issued by a trusted CA could bypass server certificate purpose validation and impersonate an RDP server. This could lead to clients accepting malicious servers, resulting in potential confidentiality breaches. The vulnerability does not affect integrity or availability directly but compromises the trust model of TLS authentication in FreeRDP.
Mitigation Recommendations
No official patch or fix is currently confirmed for this vulnerability. Users should monitor the FreeRDP vendor advisories for updates and apply official fixes once available. Until then, environments relying on strict EKU separation should consider additional network-level controls or certificate validation mechanisms to mitigate risk.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-v6mf-3jqv-cgr7
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2026-67294"]
- Database Specific Severity
- CRITICAL
- Cvss Version
- 3.1
Threat ID: 6a6e6298bf32cb7a344f9d2b
Added to database: 08/01/2026, 21:18:16 UTC
Last enriched: 08/01/2026, 21:24:33 UTC
Last updated: 09/14/2026, 10:01:32 UTC
Views: 142
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