CVE-2026-33952

Received Received - Intake

Assertion Failure DoS in FreeRDP RPC-over-HTTP Gateway Transport

Publication date: 2026-03-30

Last updated on: 2026-04-02

Assigner: GitHub, Inc.

Description

FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to version 3.24.2, an unvalidated auth_length field read from the network triggers a WINPR_ASSERT() failure in rts_read_auth_verifier_no_checks(), causing any FreeRDP client connecting through a malicious RDP Gateway to crash with SIGABRT. This is a pre-authentication denial of service affecting all FreeRDP clients using RPC-over-HTTP gateway transport. The assertion is active in default release builds (WITH_VERBOSE_WINPR_ASSERT=ON). This issue has been patched in version 3.24.2.

CVSS Scores

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Meta Information

Published

2026-03-30

Last Modified

2026-04-02

Generated

2026-07-06

AI Q&A

2026-03-31

EPSS Evaluated

2026-07-05

NVD

CVE-2026-33952

Affected Vendors & Products

Vendor	Product	Version / Range
freerdp	freerdp	to 3.24.2 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-617	The product contains an assert() or similar statement that can be triggered by an attacker, which leads to an application exit or other behavior that is more severe than necessary.

Attack-Flow Graph

Executive Summary

This vulnerability exists in FreeRDP, a free implementation of the Remote Desktop Protocol. Before version 3.24.2, an unvalidated auth_length field read from the network causes a WINPR_ASSERT() failure in the function rts_read_auth_verifier_no_checks(). This failure leads to the FreeRDP client crashing with a SIGABRT signal when connecting through a malicious RDP Gateway.

The issue is a pre-authentication denial of service affecting all FreeRDP clients that use RPC-over-HTTP gateway transport. The assertion failure is active in default release builds with verbose assertions enabled. The vulnerability has been fixed in version 3.24.2.

Impact Analysis

This vulnerability can cause FreeRDP clients to crash unexpectedly when connecting through a malicious RDP Gateway. This results in a denial of service, preventing legitimate users from establishing remote desktop connections.

Since the crash occurs before authentication, it can be exploited by attackers to disrupt services without needing valid credentials.

Mitigation Strategies

To mitigate this vulnerability, update all FreeRDP clients to version 3.24.2 or later, where the issue has been patched.

Avoid using RPC-over-HTTP gateway transport with vulnerable FreeRDP clients until they are updated.

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