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.
Published: 2026-09-15
Score: 9.2 Critical
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

Analysis and contextual insights are available on OpenCVE Cloud.

Remediation

No vendor fix or workaround currently provided.

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Tracking

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Advisories

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History

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'}


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 : Undergoing Analysis

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

Modified: 2026-09-17T20:18:54.223

Link: CVE-2026-91949

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-09-17T15:30:20Z

Weaknesses
  • CWE-693

    Protection Mechanism Failure