CVE-2026-18358
Description
A flaw was found in gnome-remote-desktop as shipped in Red Hat Enterprise Linux. When the daemon is running in system mode with RDP enabled, the incoming connection handler bypasses the connection throttler, allowing an unauthenticated remote attacker to open many parallel pre-authentication connections to the RDP listener. This can accumulate accepted sockets and pending routing-token operations until timeout, exhausting resources and preventing legitimate users from establishing RDP sessions. This issue does not affect the upstream version.
Statement
This vulnerability only affects deployments where gnome-remote-desktop is explicitly configured to run in system mode with the RDP port reachable from untrusted networks. The default user-session mode is not affected. The Moderate rather than Important severity rating reflects that exploitation requires a non-default configuration (system-mode RDP must be explicitly enabled and the listener must be network-accessible), which significantly limits the practical attack surface.
Mitigation
If system-mode RDP is not required, disable it. If it must remain enabled, restrict the RDP listener (default port 3389) to trusted hosts or management networks using host-based firewall rules.
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 | 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
Technical Impact: DoS: Crash, Exit, or Restart; DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory); DoS: Resource Consumption (Other)
If an attacker can trigger the allocation of the limited resources, but the number or size of the resources is not controlled, then the most common result is denial of service. This would prevent valid users from accessing the product, and it could potentially have an impact on the surrounding environment, i.e., the product may slow down, crash due to unhandled errors, or lock out legitimate users. For example, a memory exhaustion attack against an application could slow down the application as well as its host operating system.
Access Control,Other
Technical Impact: Bypass Protection Mechanism; Other
In some cases it may be possible to force the product to "fail open" in the event of resource exhaustion. The state of the product -- and possibly the security functionality - may then be compromised.
Acknowledgements
This issue was discovered by Found by AISLE in partnership with Red Hat.
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