CVE-2026-121407
Analyzed Analyzed - Analysis Complete

FreeRDP Remdesk Server Denial of Service via PDU Length Check

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 in the shadow server's remdesk_server_thread that allows authenticated clients to crash the process via an inverted PDU length check. Attackers can send an 8192-byte remdesk payload declaring an eight-byte PDU length to trigger a fatal Stream_Seek assertion, aborting the server and dropping sessions.

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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-2026-121407
EUVD
EUVD-2026-115939

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-20 The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.

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Executive Summary

CVE-2026-121407 is a denial of service vulnerability in FreeRDP versions before 3.32.2. It affects the shadow server's remdesk_server_thread function. Authenticated clients can exploit it by sending a crafted 8192-byte payload with an eight-byte PDU length declaration. This triggers a fatal Stream_Seek assertion, crashing the server and disconnecting sessions.

Detection Guidance

Monitor FreeRDP shadow server logs for crashes or session drops. Check for unusual network traffic on RDP ports (3389) involving large 8192-byte payloads with falsified PDU lengths. Use tools like Wireshark to inspect RDP traffic for malformed remdesk channel packets.

Impact Analysis

This vulnerability allows authenticated attackers to crash the FreeRDP shadow server, causing availability loss. Active RDP sessions are dropped, disrupting remote desktop services. No data confidentiality or integrity impact occurs, but service disruption may affect productivity and operations.

Mitigation Strategies

Upgrade FreeRDP to version 3.32.2 or later to patch the vulnerability. If upgrading is not immediately possible, restrict access to the remdesk static virtual channel in FreeRDP shadow server configurations and monitor for suspicious RDP connections.

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