CVE-2014-8101 in XFree86
Summary
by MITRE
The RandR extension in XFree86 4.2.0, X.Org X Window System (aka X11 or X) X11R6.7, and X.Org Server (aka xserver and xorg-server) before 1.16.3 allows remote authenticated users to cause a denial of service (out-of-bounds read or write) or possibly execute arbitrary code via a crafted length or index value to the (1) SProcRRQueryVersion, (2) SProcRRGetScreenInfo, (3) SProcRRSelectInput, or (4) SProcRRConfigureOutputProperty function.
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Analysis
by VulDB Data Team • 08/29/2025
The vulnerability identified as CVE-2014-8101 represents a critical security flaw within the RandR extension of X Window System implementations, specifically affecting versions prior to 1.16.3. This issue resides in the server-side processing functions that handle X11 protocol requests related to screen configuration and display management. The RandR extension, which stands for "RandR" or "Rotation and Reflection," is responsible for managing display configuration changes including screen resolution, rotation, and output properties. The vulnerability stems from inadequate input validation within four specific server procedures that process client requests for display information and configuration changes.
The technical exploitation of this vulnerability occurs through malformed input parameters sent to the server-side functions SProcRRQueryVersion, SProcRRGetScreenInfo, SProcRRSelectInput, and SProcRRConfigureOutputProperty. These functions receive length or index values that are not properly validated before being used in memory operations. When an authenticated remote attacker sends specially crafted requests containing out-of-bounds values, the server processes these inputs without sufficient bounds checking, leading to potential out-of-bounds read or write operations. This flaw falls under the Common Weakness Enumeration category CWE-129, which specifically addresses insufficient validation of length values, and can be classified as a CWE-787 out-of-bounds write or CWE-125 out-of-bounds read depending on the specific execution path taken by the vulnerable code.
The operational impact of this vulnerability is severe and multifaceted, encompassing both denial of service conditions and potential arbitrary code execution capabilities. An authenticated attacker with network access to a vulnerable X server can trigger memory corruption that may result in immediate service disruption through process crashes or system instability. More concerning is the potential for remote code execution, which would allow attackers to gain control over the affected system running the X server. This represents a significant risk in environments where X11 servers are exposed to untrusted networks, such as remote desktop services, kiosks, or multi-user systems where authentication is required but network exposure remains a concern. The vulnerability affects a wide range of systems including Linux distributions, Unix-based systems, and any platform implementing X.Org Server versions prior to 1.16.3, making it particularly dangerous in enterprise environments where such systems are commonly deployed.
From a threat modeling perspective, this vulnerability aligns with ATT&CK technique T1059.007 for command and script interpreter, as successful exploitation could lead to arbitrary code execution with the privileges of the X server process. The attack surface is particularly concerning given that X11 servers are often run with elevated privileges and may be accessible across network boundaries. Organizations should implement immediate mitigation strategies including applying the relevant security patches from X.Org Server 1.16.3 or later, implementing network segmentation to limit access to X servers, and monitoring for suspicious X11 protocol traffic patterns. Additionally, system administrators should consider disabling unnecessary X11 features and implementing proper access controls to minimize the risk of exploitation. The vulnerability demonstrates the importance of robust input validation in server-side applications and highlights the critical need for regular security updates in widely deployed system components such as X Window System implementations.