CVE-2026-121391
Description
A flaw was found in FreeRDP. When parallel-device redirection is enabled, a malicious Remote Desktop Protocol (RDP) server can cause a Denial of Service (DoS) on a connecting client by sending repeated device open requests. Due to a resource management flaw, the client fails to close previous file descriptors upon receiving subsequent requests. This behavior enables a hostile server to exhaust the client's available file handles, ultimately causing the FreeRDP client process to crash.
Statement
This vulnerability is rated as Moderate impact for Red Hat products because exploitation requires a client to initiate an RDP session to an untrusted server while explicitly enabling parallel device redirection, limiting the failure impact strictly to client denial of service. Under standard deployments, parallel port redirection is not enabled by default, requiring specific user configuration to expose the affected functionality. Furthermore, the issue only exhausts client-side file descriptors without allowing code execution or compromising the host system outside of the terminating FreeRDP process.
Mitigation
Disable parallel device redirection when connecting to remote RDP endpoints.
Ensure that client connection configurations or command-line invocations do not enable parallel device redirection (such as omitting the `/parallel` option). Additionally, restrict connections strictly to trusted and authenticated RDP hosts to prevent untrusted servers from triggering client resource exhaustion.
Caveats:
Disabling parallel port redirection prevents remote RDP sessions from interacting with local parallel devices.
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 | 4.3 | N/A | 4.3 |
| 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 | Low | N/A | Low |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Resource Consumption (Other); DoS: Resource Consumption (Memory); DoS: Resource Consumption (CPU)
An attacker that can influence the allocation of resources that are not properly released could deplete the available resource pool and prevent all other processes from accessing the same type of resource. Frequently-affected resources include memory, CPU, disk space, power or battery, etc.
Frequently Asked Questions
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