Critical severity9.3NVD Advisory· Published Sep 15, 2026

CVE-2026-91949

Description

FreeRDP server versions before 3.31.0 contain a protocol negotiation bypass vulnerability that allows unauthenticated attackers to establish RDSTLS connections despite server policy disabling them. Attackers can send incompatible protocol requests, receive negotiation failures, then complete TLS handshake and enter RDSTLS to bypass pre-authentication transport restrictions.

Affected products

Freerdp/Freerdpllm-fuzzy
Range: <3.31.0

Patches

Vulnerability mechanics

References

github.com/FreeRDP/FreeRDP/security/advisories/GHSA-x7v6-xfx3-52j6nvd
www.vulncheck.com/advisories/freerdp-3.0.0-through-3.30.0-protocol-negotiation-bypassnvd

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epss	0.000
exploit	0.000
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patch	-0.070
ransomware	0.000