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.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.27%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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 4.0
- 9.3 CRITICALCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M
- EPSS
- 0.27% probability · 19th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-295
- Affected
- freerdp/freerdp
- Source
- disclosure@vulncheck.com
References
- https://github.com/FreeRDP/FreeRDP/commit/f3b4347105114fe7453828736bea069999af319fPatch
- https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-89c6-jjrw-96h4Exploit, Vendor Advisory
- https://www.vulncheck.com/advisories/freerdp-before-tls-certificate-eku-bypassPatch, Third Party Advisory
- https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-89c6-jjrw-96h4Exploit, Vendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.