CVE-2026-121394
Description
A flaw was found in FreeRDP. This vulnerability allows a malicious Remote Desktop Protocol (RDP) server to cause a Denial of Service (DoS) by crashing the connected client. When a user connects to an attacker-controlled server with RemoteFX decoding enabled, the server can transmit a specially crafted graphics stream. This triggers an internal assertion failure in the decoder, causing the client application to terminate abruptly.
Statement
A flaw was found in FreeRDP. A remote attacker controlling an RDP server can cause a connected FreeRDP client to crash via a crafted packet triggering an assertion failure in the RemoteFX decoder, resulting in a denial of service. The user must connect to an attacker-controlled server and RemoteFX must be enabled.
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 | 6.5 | N/A | 6.5 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | Required | N/A | Required |
| 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:R/S:U/C:N/I:N/A:H
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Crash, Exit, or Restart
While assertion is good for catching logic errors and reducing the chances of reaching more serious vulnerability conditions, an attacker can still cause a denial of service if they can trigger an assert statement, and if the scope of the assert() extends beyond the attacker's own session. For example, if a server handles multiple simultaneous connections, if an assert() occurs in one single connection that causes all other connections to be dropped, this could be a significant denial of service.
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