CVE-2026-121395
Undergoing Analysis Undergoing Analysis - In Progress

RemoteFX Decoder Assertion Failure in FreeRDP

Publication date: 2026-11-03

Last updated on: 2026-11-03

Assigner: VulnCheck

Description
FreeRDP from 3.17.0 before 3.32.2 contains an assertion failure in the RemoteFX differential decoder when verbose WinPR assertions are enabled. A malicious RDP server can send a crafted RemoteFX tile with adjacent LL3 coefficients summing beyond signed 16-bit range to abort the client process.

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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-2026-121395
EUVD
EUVD-2026-115927

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
FreeRDP FreeRDP 3.17.0

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Exploitability

CWE
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KEV
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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.

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Executive Summary

This vulnerability is a Denial of Service (DoS) flaw in FreeRDP versions 3.17.0 through 3.32.1. It occurs when verbose WinPR assertions are enabled, causing an assertion failure in the RemoteFX differential decoder. A malicious RDP server can exploit this by sending a crafted RemoteFX tile with coefficients that exceed the signed 16-bit range, leading the client process to abort.

Detection Guidance

To detect this vulnerability, check if your FreeRDP client version is between 3.17.0 and 3.32.1. Run 'xfreerdp --version' or 'freerdp2 --version' to verify the installed version. If verbose WinPR assertions are enabled (WITH_VERBOSE_WINPR_ASSERT=ON), the system is potentially vulnerable.

Impact Analysis

The vulnerability allows an attacker to terminate the FreeRDP client by sending malicious RemoteFX data. This results in a denial of service, disrupting the user's remote desktop session. It does not compromise confidentiality or integrity of data, nor does it cause memory corruption.

Mitigation Strategies
  • Upgrade FreeRDP to version 3.32.2 or later if available.
  • Disable verbose WinPR assertions by ensuring WITH_VERBOSE_WINPR_ASSERT=OFF during compilation.
  • Avoid connecting to untrusted RDP servers until patched.

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