CVE-2026-109952
Received Received - Intake

FreeRDP Security Protocol Downgrade Vulnerability

Publication date: 2026-10-13

Last updated on: 2026-10-13

Assigner: VulnCheck

Description
The FreeRDP client 3.0.0 before 3.32.0 does not check a server-selected PROTOCOL_RDSTLS or PROTOCOL_HYBRID_EX against its enabled protocol set in nego_process_negotiation_response(), allowing a security protocol downgrade. A malicious server or man-in-the-middle can select RDSTLS to override /sec:nla pinning, complete authentication with an all-zero cookie, and receive the user's cleartext password in the Client Info PDU.

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Meta Information

Published
2026-10-13
Last Modified
2026-10-13
Generated
2026-10-13
AI Q&A
2026-10-13
EPSS Evaluated
N/A
NVD
CVE-2026-109952
EUVD
EUVD-2026-98656

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
FreeRDP FreeRDP 3.0.0

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-757 A protocol or its implementation supports interaction between multiple actors and allows those actors to negotiate which algorithm should be used as a protection mechanism such as encryption or authentication, but it does not select the strongest algorithm that is available to both parties.

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Executive Summary

CVE-2026-109952 is a vulnerability in FreeRDP versions 3.0.0 to 3.31.0 where the client does not validate the server-selected security protocol against its enabled protocols. This allows an attacker to force the use of a weaker protocol like RDSTLS, bypassing intended security settings such as NLA pinning. The attacker can then capture the user's cleartext password during authentication.

Detection Guidance

To detect this vulnerability, check the FreeRDP client version on your system. Run: freerdp2 /v:example.com /cert-ignore. If the version is between 3.0.0 and 3.31.0, the system is vulnerable. Monitor network traffic for unexpected RDSTLS or HYBRID_EX protocol negotiations.

Impact Analysis

If exploited, this vulnerability could allow an attacker on the same network or controlling a proxy to intercept and decrypt your credentials. The attacker could downgrade the security protocol, bypass authentication requirements, and capture your password in plaintext during login attempts.

Compliance Impact

This vulnerability could lead to unauthorized access to sensitive data, violating confidentiality requirements in GDPR and HIPAA. Exposure of cleartext passwords and bypassed authentication may result in non-compliance with data protection and security control standards.

Mitigation Strategies

Upgrade FreeRDP to version 3.32.0 or later immediately. If upgrading is not possible, disable RDSTLS and HYBRID_EX protocols in client configurations. Avoid using untrusted networks or proxies for RDP connections.

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