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Vulnerability record · CVE-2026-67294 · published 1 August 2026

CVE-2026-67294: Freerdp improper certificate validation vulnerability

Freerdp · Freerdp

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.

9.3 CVSS 4.0 Critical EPSS 0.36% · top 72.5% CWE-295 · Improper certificate validation
9.3CVSS 4.0 base score
0.36%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
4References, 2 tagged exploit
11 Sep 2026Last modified by NVD

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/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:

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/FreeRDP/FreeRDP/commit/f3b4347105114fe7453828736bea069999af319f Patch
https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-89c6-jjrw-96h4 ExploitVendor Advisory
https://www.vulncheck.com/advisories/freerdp-before-tls-certificate-eku-bypass PatchThird Party Advisory
https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-89c6-jjrw-96h4 ExploitVendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-67294), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.