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.

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Fixes

Solution

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Workaround

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History

Mon, 21 Sep 2026 12:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-358
References
Metrics threat_severity

None

threat_severity

Critical


Thu, 17 Sep 2026 20:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Tue, 15 Sep 2026 15:30:00 +0000

Type Values Removed Values Added
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.
Title FreeRDP 3.0.0 through 3.30.0 Protocol Negotiation Bypass
First Time appeared Freerdp
Freerdp freerdp
Weaknesses CWE-693
CPEs cpe:2.3:a:freerdp:freerdp:*:*:*:*:*:*:*:*
Vendors & Products Freerdp
Freerdp freerdp
References
Metrics cvssV3_1

{'score': 9.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N'}

cvssV4_0

{'score': 9.2, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:L/VA:N/SC:H/SI:L/SA:N'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: VulnCheck

Published:

Updated: 2026-09-17T19:28:33.068Z

Reserved: 2026-09-15T11:07:34.398Z

Link: CVE-2026-91949

cve-icon Vulnrichment

Updated: 2026-09-17T19:15:28.847Z

cve-icon NVD

Status : Analyzed

Published: 2026-09-15T16:17:48.653

Modified: 2026-09-24T12:14:46.820

Link: CVE-2026-91949

cve-icon Redhat

Severity : Critical

Publid Date: 2026-09-15T15:18:07Z

Links: CVE-2026-91949 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-09-21T15:00:18Z

Weaknesses