CVE-2026-121964
Undergoing Analysis Undergoing Analysis - In Progress

Heap Overflow in FreeRDP via Malicious RD Gateway RPC

Vulnerability report for CVE-2026-121964, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.

Publication date: 2026-11-04

Last updated on: 2026-11-04

Assigner: VulnCheck

Description

FreeRDP before 3.32.2 contains a heap-based buffer overflow in the RD Gateway RPC client, where rpc_client_recv_fragment writes BIND_ACK and ALTER_CONTEXT_RESP fragments into a persistent PDU stream after checking only total capacity rather than remaining capacity from the current stream position. A malicious or compromised RD Gateway can send crafted RPC fragments with manipulated alloc_hint and frag_length values to overwrite client heap memory with attacker-controlled data, causing a crash or potentially arbitrary code execution.

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Meta Information

Published
2026-11-04
Last Modified
2026-11-04
Generated
2026-11-04
AI Q&A
2026-11-04
EPSS Evaluated
N/A
NVD
EUVD

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
FreeRDP FreeRDP 0

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-122 A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().

Attack-Flow Graph

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Executive Summary

CVE-2026-121964 is a heap-based buffer overflow in FreeRDP before version 3.32.2. It occurs in the RD Gateway RPC client's rpc_client_recv_fragment function, which fails to check remaining buffer capacity before writing data. A malicious RD Gateway can send crafted RPC fragments with manipulated values to overwrite client heap memory, potentially causing crashes or arbitrary code execution.

Detection Guidance

Detecting this vulnerability requires checking FreeRDP versions and monitoring network traffic for suspicious RPC fragments. Use 'xfreerdp --version' to verify installed FreeRDP version. If version is below 3.32.2, the system is vulnerable. Network monitoring tools like Wireshark can inspect RPC fragments for manipulated alloc_hint and frag_length values targeting FreeRDP clients.

Impact Analysis

This vulnerability allows attackers to crash FreeRDP clients or execute arbitrary code on systems running vulnerable versions. If exploited, it could compromise the confidentiality, integrity, and availability of affected systems, especially those using FreeRDP for remote desktop connections.

Mitigation Strategies

Immediately upgrade FreeRDP to version 3.32.2 or later. Disable RD Gateway connections if not required. Apply network-level mitigations like blocking untrusted RPC traffic. Monitor systems for crashes or unusual memory usage patterns that may indicate exploitation attempts.

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