CVE-2020-11095 in FreeRDP
Summary
by MITRE
In FreeRDP before version 2.1.2, an out of bound reads occurs resulting in accessing a memory location that is outside of the boundaries of the static array PRIMARY_DRAWING_ORDER_FIELD_BYTES. This is fixed in version 2.1.2.
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Analysis
by VulDB Data Team • 05/19/2025
The vulnerability identified as CVE-2020-11095 represents a critical memory safety issue within the FreeRDP remote desktop protocol implementation that affects versions prior to 2.1.2. This flaw manifests as an out-of-bounds read condition that occurs during the processing of remote desktop graphics commands, specifically when handling primary drawing order field bytes. The vulnerability stems from insufficient bounds checking in the code that manages the static array PRIMARY_DRAWING_ORDER_FIELD_BYTES, which serves as a critical component in the parsing and interpretation of graphics data within the RDP protocol stack.
The technical implementation of this vulnerability involves a classic buffer over-read scenario where the FreeRDP client or server processes incoming graphics data without proper validation of array access boundaries. When the application encounters a malformed or specially crafted graphics command, it attempts to read memory locations beyond the allocated bounds of the PRIMARY_DRAWING_ORDER_FIELD_BYTES array. This condition creates a potential pathway for information disclosure, system instability, or in worst-case scenarios, arbitrary code execution depending on the specific memory layout and exploitation conditions. The flaw demonstrates poor input validation practices and highlights the importance of robust bounds checking in network protocol implementations.
The operational impact of this vulnerability extends across various deployment scenarios where FreeRDP is utilized for remote desktop connections, including enterprise environments, cloud infrastructure, and remote work solutions. Attackers could potentially exploit this condition by sending malicious graphics data to a vulnerable FreeRDP instance, leading to denial of service conditions, memory corruption, or information leakage that might reveal sensitive system information. The vulnerability's exploitation potential is particularly concerning given that FreeRDP is widely deployed in production environments and serves as a core component for remote access solutions. This issue aligns with CWE-129, which specifically addresses insufficient bounds checking, and represents a significant concern for organizations relying on RDP implementations for remote access management.
Organizations should prioritize immediate remediation by upgrading to FreeRDP version 2.1.2 or later, which includes the necessary bounds checking fixes for this vulnerability. Additionally, network segmentation and monitoring of RDP traffic can provide defensive measures against potential exploitation attempts. Security teams should implement continuous vulnerability assessment procedures to identify and remediate similar issues in other protocol implementations. The fix addresses the root cause by implementing proper array boundary validation and ensuring that all graphics data processing operations respect the allocated memory boundaries, thereby preventing unauthorized memory access patterns that could be leveraged for malicious purposes. This vulnerability serves as a reminder of the critical importance of memory safety in network protocol implementations and the necessity of rigorous code review processes to prevent similar issues in other software components.