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 Details
- CVSS 4.0 Base Score: 9.3 (CRITICAL)
- CVSS 4.0 Vector: (CVSS: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/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X)
- CVSS 3.1 Base Score: 5.9
- CVSS 3.1 Vector: (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N)
Covered by Rapid7
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Amazon_linux_2023 | — | Upgrade freerdpUpgrade freerdp-debuginfoUpgrade libwinpr-debuginfoUpgrade freerdp-serverUpgrade freerdp-libsUpgrade libwinpr-develUpgrade freerdp-debugsourceUpgrade freerdp-develUpgrade libwinprUpgrade freerdp-server-debuginfoUpgrade freerdp-libs-debuginfo | Sep 1, 2026 | Aug 1, 2026 |
| Redhat_linux | — | No solution exists | Aug 4, 2026 | Aug 1, 2026 |
| Ubuntu | — | Upgrade freerdp3 | Aug 17, 2026 | Aug 1, 2026 |
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