CVE-2026-121959
Description
A flaw was found in FreeRDP. A malicious Remote Desktop (RD) Gateway or network attacker can cause a Denial of Service (DoS) by sending a truncated WebSocket data frame followed by a Transport Layer Security (TLS) connection shutdown. Due to improper handling of the incomplete payload when the connection closes, the client enters an infinite loop, consuming excessive Central Processing Unit (CPU) resources until the application is terminated.
Statement
This vulnerability is rated as having Moderate impact because exploitation requires a client to initiate a connection to a compromised or untrusted Remote Desktop Gateway, limiting the blast radius to client-side denial of service. In typical Red Hat Enterprise Linux environments, FreeRDP is used as an interactive client utility rather than a persistent background service. An untrusted gateway responding with an incomplete transport payload before terminating the secure session causes the client process to loop indefinitely and consume processor capacity, without threatening system data confidentiality or memory integrity.
Mitigation
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
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).
The following CVSS metrics and score provided are preliminary and subject to review.
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: Resource Consumption (CPU); DoS: Resource Consumption (Memory); DoS: Amplification
An infinite loop will cause unexpected consumption of resources, such as CPU cycles or memory. The software's operation may slow down, or cause a long time to respond.
Frequently Asked Questions
Not sure what something means? Check out our Security Glossary.
Want to get errata notifications? Sign up here.
