CVE-2026-91958
Received Received - Intake

Heap Out-of-Bounds Read/Write in FreeRDP

Publication date: 2026-09-15

Last updated on: 2026-09-15

Assigner: VulnCheck

Description
FreeRDP versions before 3.31.0 fail to validate MonitorIds array values when parsing RDP connection files, allowing unbounded array indexing in xf_detect_monitors. Attackers can craft a malicious RDP file with an out-of-range selectedmonitors value to trigger out-of-bounds heap read and write operations when opened in xfreerdp.

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Meta Information

Published
2026-09-15
Last Modified
2026-09-15
Generated
2026-09-15
AI Q&A
2026-09-15
EPSS Evaluated
N/A
NVD
CVE-2026-91958
EUVD
EUVD-2026-78634

Affected Vendors & Products

Showing 2 associated CPEs
Vendor Product Version / Range
freerdp freerdp From 3.11.0 (inc) to 3.30.0 (inc)
freerdp freerdp to 3.31.0 (exc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-125 The product reads data past the end, or before the beginning, of the intended buffer.

Attack-Flow Graph

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Executive Summary

CVE-2026-91958 is a heap buffer overflow vulnerability in FreeRDP versions before 3.31.0. It occurs when parsing RDP connection files due to missing validation of MonitorIds array values. Attackers can craft malicious files with out-of-range selectedmonitors values, causing out-of-bounds heap read and write operations when opened in xfreerdp.

Detection Guidance

Check FreeRDP version with 'xfreerdp --version' or 'apt show freerdp2-x11'. Monitor for crashes when opening RDP files. Inspect logs for heap corruption errors during X11 client processing.

Impact Analysis

This vulnerability allows attackers to execute arbitrary code or cause denial-of-service conditions on systems running vulnerable FreeRDP versions. It requires only that a victim opens a malicious RDP file with an X11-based FreeRDP client (xfreerdp). The impact includes potential data corruption, application crashes, or unauthorized system access.

Mitigation Strategies

Upgrade FreeRDP to version 3.31.0 or later. Avoid opening untrusted RDP files. Disable X11-based clients if possible. Monitor for suspicious RDP file activity.

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