CVE-2026-91949

FreeRDP 3.0.0 through 3.30.0 Protocol Negotiation Bypass

CRITICAL
9.3
CVSS Score
Published: September 15, 2026 at 03:18 PM UTC
Updated: September 24, 2026 at 12:27 PM UTC
1 product affected across 1 vendorFreeRDP

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Severity
CRITICAL9.3
Exploit prediction
EPSS 0.6%
SSVC
No known exploit

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

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

3.0.0 ≤ v < 3.31.03.0.0
Vendor states this is fixed in 3.31.0 (unaffected)

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

SSVC — Action Prioritization

SSVCNo known exploitAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

9.3CRITICALVulnCheck
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
CHANGED
Confidentiality
HIGH
Integrity
LOW
Availability
NONE
Vector?

Quick Info

StatusANALYZED
CWE
CWE-693

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