CVE-2026-109245 FreeRDP CVE debrief

Who should care

Defenders responsible for FreeRDP deployments, Azure AD authentication flows, and systems using OAuth authorization codes should assess exposure and prioritize verification and remediation.

Why it matters

The CVE-2026-109245 vulnerability in FreeRDP 3.0.0 before 3.32.0 requires defenders to verify and upgrade to prevent on-path attacks impersonating login.microsoftonline.com in Azure AD authentication flows.

• On-path attackers can impersonate login.microsoftonline.com to capture OAuth authorization codes.
• The vulnerability allows substitution of the OpenID discovery document.
• Defenders need to verify and upgrade to FreeRDP version 3.32.0 or later.
• The impact of potential exploitation on Azure AD authentication flows requires verification.

Technical summary

The vulnerability is caused by improper certificate validation in freerdp_http_request() in libfreerdp/utils/http.c, which completes TLS handshakes without verifying the server certificate chain. This allows on-path attackers to impersonate login.microsoftonline.com in the Azure AD authentication flow to capture OAuth authorization codes and substitute the OpenID discovery document. The vulnerability affects FreeRDP 3.0.0 before 3.32.0 and requires defenders to verify and upgrade to prevent on-path attacks impersonating login.microsoftonline.com in Azure AD authentication flows.

Defensive priority

Defenders should prioritize verifying and upgrading to FreeRDP version 3.32.0 or later to address the improper certificate validation vulnerability.

Recommended defensive actions

• Verify and upgrade to FreeRDP version 3.32.0 or later
• Review and update Azure AD authentication flows to ensure secure certificate validation
• Monitor for potential on-path attacks impersonating login.microsoftonline.com
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up
• Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance
• Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed
• Check relevant monitoring, detection, and logs for exposed assets that need extra review

Evidence notes

The CVE record and source item provide details on the vulnerability in FreeRDP 3.0.0 before 3.32.0. However, there is limited information on potential exploitation or affected systems. Defenders should verify and review compensating controls for exposed systems while remediation is scheduled and verified. The vulnerability allows on-path attackers to impersonate login.microsoftonline.com in the Azure AD authentication flow to capture OAuth authorization codes and substitute the OpenID discovery document.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.