CVE-2026-109943
Description
A flaw was found in FreeRDP. A malicious Remote Desktop Protocol (RDP) server can trigger a Denial of Service (DoS) by causing a connecting client to crash. When asynchronous update processing is enabled, sending specially crafted polygon drawing orders can cause a double-free memory error during message handling, terminating the client connection.
Statement
This flaw is rated Moderate because a malicious or compromised RDP server can crash the FreeRDP client when async-update polygon order handling is used, causing a denial of service for the connecting user. Exploitation requires the user to initiate a connection (UI:R). Confidentiality and integrity are not impacted. Red Hat platform safeguards such as ASLR, NX, and FORTIFY_SOURCE do not remove the crash impact, so Availability remains High.
Mitigation
Restrict FreeRDP clients to trusted RDP servers and networks.
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
Red Hat CVSS v3 Score Explanation
Red Hat CVSS reflects FreeRDP exposure after applying client/server interaction model. Score 6.5 maps to MODERATE.
Understanding the Weakness (CWE)
Integrity,Confidentiality,Availability
Technical Impact: Modify Memory; Execute Unauthorized Code or Commands
When a program calls free() twice with the same argument, the program's memory management data structures may become corrupted, potentially leading to the reading or modification of unexpected memory addresses. This corruption can cause the program to crash or, in some circumstances, cause two later calls to malloc() to return the same pointer. If malloc() returns the same value twice and the program later gives the attacker control over the data that is written into this doubly-allocated memory, the program becomes vulnerable to a buffer overflow attack. Doubly freeing memory may result in a write-what-where condition, allowing an attacker to execute arbitrary code.
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