CVE-2026-25997 – This CVE describes a use-after-free vulnerabili... (How to Fix)

Q: What is the severity of CVE-2026-25997?

CVE-2026-25997 has a CVSS score of 9.8 (CRITICAL). This CVE describes a use-after-free vulnerability in FreeRDP's clipboard handling for X11 clients. When FreeRDP automatically reconnects, one thread frees clipboard format memory while another thread is still accessing it, potentially causing crashes or arbitrary code execution. This affects FreeRDP users connecting via X11 on Linux/Unix systems.

📋 TL;DR

This CVE describes a use-after-free vulnerability in FreeRDP's clipboard handling for X11 clients. When FreeRDP automatically reconnects, one thread frees clipboard format memory while another thread is still accessing it, potentially causing crashes or arbitrary code execution. This affects FreeRDP users connecting via X11 on Linux/Unix systems.

💻 Affected Systems

Products:

FreeRDP

Versions: All versions prior to 3.23.0

Operating Systems: Linux, Unix-like systems with X11

Default Config Vulnerable: ⚠️ Yes

Notes: Only affects X11 client implementations of FreeRDP. Windows clients and other platforms are not affected.

📦 What is this software?

Freerdp by Freerdp

View all CVEs affecting Freerdp →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Remote code execution with the privileges of the FreeRDP process, potentially leading to full system compromise.

🟠

Likely Case

Application crash or denial of service, with potential for information disclosure or limited code execution.

🟢

If Mitigated

Application crash only, with no privilege escalation beyond the FreeRDP process context.

🌐 Internet-Facing: MEDIUM - Requires an attacker to be able to trigger clipboard operations and auto-reconnect scenarios.

🏢 Internal Only: MEDIUM - Same technical risk but limited to internal attackers with network access to FreeRDP sessions.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Exploitation requires triggering specific race conditions during clipboard operations and auto-reconnect scenarios.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: 3.23.0

Vendor Advisory: https://github.com/FreeRDP/FreeRDP/releases/tag/3.23.0

Restart Required: Yes

Instructions:

1. Download FreeRDP 3.23.0 or later from the official repository. 2. Compile and install according to your distribution's package management or from source. 3. Restart any FreeRDP client sessions.

🔧 Temporary Workarounds

Disable clipboard redirection

linux

Prevent clipboard synchronization between client and server to avoid triggering the vulnerable code path.

xfreerdp /clipboard- /v:TARGET

Disable auto-reconnect

linux

Prevent automatic reconnection attempts that trigger the race condition.

xfreerdp /reconnect- /v:TARGET

🧯 If You Can't Patch

Use alternative RDP clients that are not affected by this vulnerability
Implement network segmentation to limit access to FreeRDP services

🔍 How to Verify

Check if Vulnerable:

Check FreeRDP version with 'xfreerdp --version' and verify it's below 3.23.0

Check Version:

xfreerdp --version | head -1

Verify Fix Applied:

Confirm version is 3.23.0 or higher with 'xfreerdp --version'

📡 Detection & Monitoring

Log Indicators:

FreeRDP crash logs with segmentation faults
Application errors mentioning clipboard or xf_cliprdr

Network Indicators:

RDP session reconnections followed by client crashes

SIEM Query:

source="freerdp.log" AND ("segmentation fault" OR "use-after-free" OR "clipboard")

📊 Metadata

CVE ID: CVE-2026-25997

CVSS v3 Score: 9.8 (CRITICAL)

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CWE: CWE-416

Published: February 25, 2026

Last Updated: February 27, 2026

🔗 References

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