CVE-2026-121386
Description
A flaw was found in FreeRDP. A malicious Remote Desktop Protocol (RDP) server or a man-in-the-middle network attacker can cause a Denial of Service (DoS) by sending malformed PNG or JPEG image data during clipboard synchronization. Due to missing error handling in the image parsing routines, processing the invalid image buffer causes the client application to abruptly abort or exit.
Statement
This vulnerability is rated as an Important impact for Red Hat products because an untrusted remote desktop host or network intermediary can terminate the client session unexpectedly without prior authentication. Although this defect causes application termination rather than remote code execution, it directly impacts the availability of user sessions in enterprise environments. Exploitation requires an established connection to a malicious RDP endpoint or interception by an adversary on the network path processing shared clipboard content.
Mitigation
Disable clipboard redirection for RDP connections.
When launching sessions with the xfreerdp command-line utility, explicitly disable the clipboard channel:
xfreerdp -clipboard /v:<server_address>
When connecting via graphical clients, disable clipboard synchronization within the respective connection profile preferences.
Caveats:
Disabling clipboard redirection prevents transferring text, images, or files between the local system and the remote session.
Warning:
Changes apply to new connections; any active RDP sessions must be disconnected and restarted for the setting to take effect.
--- CME Mitigation Guidance (2026-11-04) ---
Disclaimer: The following mitigation solutions are provided as a courtesy, pending the application of an official patch. This content was generated utilizing AI tools in conjunction with data from https://cmetaxonomy.org. Customers are advised to independently evaluate and test these temporary mitigations within their own infrastructure.
The highest-value action is to disable clipboard redirection in FreeRDP client connections to prevent processing untrusted image buffers through WinPR: upgrade to FreeRDP 3.32.2 (or the fixed Freerdp builds), which install setjmp error handlers for libpng and libjpeg in winpr_read_png_from_buffer, winpr_convert_from_jpeg, and winpr_convert_to_jpeg, closing all 2 injection vectors (malformed PNG clipboard payload, truncated JPEG clipboard payload). Until patched, this is a concern on FreeRDP client sessions with clipboard redirection enabled connecting across untrusted networks or to untrusted RDP servers, so Disable clipboard redirection by using the -clipboard flag in xfreerdp or disabling clipboard synchronization in graphical connection profiles, then disconnect and restart active sessions. These controls limit blast radius and contain exploitation, but they do not fix the underlying missing image library error-handling defect — apply the upstream patch to fully remediate.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.5 | N/A | 7.5 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | None |
| Integrity Impact | None | N/A | None |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Availability,Confidentiality
Technical Impact: DoS: Crash, Exit, or Restart; Read Application Data
An uncaught exception could cause the system to be placed in a state that could lead to a crash, exposure of sensitive information, or other unintended behaviors.
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