CVE-2023-40186 in FreeRDP
Summary
by MITRE • 09/01/2023
FreeRDP is a free implementation of the Remote Desktop Protocol (RDP), released under the Apache license. Affected versions are subject to an IntegerOverflow leading to Out-Of-Bound Write Vulnerability in the `gdi_CreateSurface` function. This issue affects FreeRDP based clients only. FreeRDP proxies are not affected as image decoding is not done by a proxy. This issue has been addressed in versions 2.11.0 and 3.0.0-beta3. Users are advised to upgrade. There are no known workarounds for this issue.
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Analysis
by VulDB Data Team • 02/16/2025
The vulnerability CVE-2023-40186 represents a critical integer overflow condition within FreeRDP's gdi_CreateSurface function that can lead to out-of-bounds write operations. This flaw exists in the remote desktop protocol implementation where the software fails to properly validate input parameters during surface creation operations, creating a scenario where maliciously crafted RDP packets could trigger memory corruption. The vulnerability specifically affects FreeRDP client implementations that process RDP graphics data, while proxy implementations remain unaffected due to their different architectural approach to image decoding. The integer overflow occurs when processing dimensions or coordinates that exceed the maximum representable value for the target data type, causing subsequent memory operations to write beyond allocated boundaries.
The technical exploitation of this vulnerability falls under CWE-190, which categorizes integer overflow conditions that can result in memory corruption and arbitrary code execution. This particular flaw demonstrates how improper input validation in graphics processing components can create dangerous memory access patterns that attackers can leverage to execute malicious code. The operational impact extends beyond simple memory corruption as it represents a potential vector for remote code execution within RDP client environments where attackers could craft specially formatted RDP graphics data to trigger the overflow condition. The vulnerability affects organizations relying on FreeRDP clients for remote desktop connectivity, potentially compromising endpoints that process untrusted RDP connections.
Security researchers have identified this issue as part of the broader ATT&CK framework's technique T1059, which encompasses execution through remote services, particularly when considering the potential for attackers to establish persistent access through compromised RDP clients. The vulnerability's presence in FreeRDP versions prior to 2.11.0 and 3.0.0-beta3 creates a window of exposure for organizations that have not yet updated their implementations. The fact that no workarounds exist means that organizations must rely entirely on upgrading to patched versions to achieve protection. This vulnerability underscores the importance of proper input validation in graphics processing libraries and highlights how seemingly benign operations like surface creation can become attack vectors when integer overflow conditions are not properly addressed. The fix implemented in the patched versions includes enhanced bounds checking and integer overflow detection mechanisms that prevent malicious input from causing memory corruption during graphics processing operations. Organizations should immediately prioritize upgrading their FreeRDP implementations to mitigate this risk and maintain secure remote desktop connectivity.