CVE-2026-121401
Modified Modified - Updated After Analysis

FreeRDP Denial of Service via Unauthenticated Extended Auth Packet

Publication date: 2026-11-03

Last updated on: 2026-11-03

Assigner: VulnCheck

Description
FreeRDP before 3.32.2 contains a denial of service vulnerability where rdg_process_packet dispatches a PKT_TYPE_EXTENDED_AUTH_MSG without verifying negotiated mode or auth context. A malicious or compromised RD Gateway can send the extended-auth packet before tunnel authentication, triggering a null-pointer dereference that crashes the client.

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Meta Information

Published
2026-11-03
Last Modified
2026-11-03
Generated
2026-11-03
AI Q&A
2026-11-03
EPSS Evaluated
N/A
NVD
CVE-2026-121401
EUVD
EUVD-2026-115933

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
freerdp freerdp to 3.32.2 (exc)

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Exploitability

CWE
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KEV
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CWE ID Description
CWE-476 The product dereferences a pointer that it expects to be valid but is NULL.

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Executive Summary

CVE-2026-121401 is a denial of service vulnerability in FreeRDP versions before 3.32.2. A malicious or compromised RD Gateway can send a specific extended-authentication packet (PKT_TYPE_EXTENDED_AUTH_MSG) before tunnel authentication completes. This causes a null-pointer dereference in the client, crashing it with exit codes 134 or 139.

Detection Guidance

Monitor FreeRDP client crashes or connection failures when connecting through an RD Gateway. Check logs for null-pointer dereference errors or exit codes 134/139. Use network traffic analysis tools like Wireshark to inspect packets for PKT_TYPE_EXTENDED_AUTH_MSG sent before authentication completion.

Impact Analysis

The vulnerability allows an attacker to crash the FreeRDP client by sending a malformed packet, resulting in a denial of service. It does not enable memory corruption, data access, or code execution. Users may experience unexpected client crashes when connecting through a compromised RD Gateway.

Mitigation Strategies

Upgrade FreeRDP to version 3.32.2 or later. Disable RD Gateway connections if not required. Configure firewalls to block unauthorized RD Gateway traffic. Monitor for suspicious extended-auth packets before authentication.

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