CVE-2014-8095 in XFree86
Summary
by MITRE
The XInput extension in X.Org X Window System (aka X11 or X) X11R4 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) SProcXChangeDeviceControl, (2) ProcXChangeDeviceControl, (3) ProcXChangeFeedbackControl, (4) ProcXSendExtensionEvent, (5) SProcXIAllowEvents, (6) SProcXIChangeCursor, (7) ProcXIChangeHierarchy, (8) SProcXIGetClientPointer, (9) SProcXIGrabDevice, (10) SProcXIUngrabDevice, (11) ProcXIUngrabDevice, (12) SProcXIPassiveGrabDevice, (13) ProcXIPassiveGrabDevice, (14) SProcXIPassiveUngrabDevice, (15) ProcXIPassiveUngrabDevice, (16) SProcXListDeviceProperties, (17) SProcXDeleteDeviceProperty, (18) SProcXIListProperties, (19) SProcXIDeleteProperty, (20) SProcXIGetProperty, (21) SProcXIQueryDevice, (22) SProcXIQueryPointer, (23) SProcXISelectEvents, (24) SProcXISetClientPointer, (25) SProcXISetFocus, (26) SProcXIGetFocus, or (27) SProcXIWarpPointer function.
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Analysis
by VulDB Data Team • 08/29/2025
The vulnerability described in CVE-2014-8095 represents a critical security flaw within the XInput extension of the X Window System, specifically affecting X11R4 and X.Org Server versions prior to 1.16.3. This issue stems from improper validation of user-supplied input parameters within multiple XInput extension functions, creating a pathway for authenticated remote attackers to manipulate system resources through crafted requests. The vulnerability is particularly concerning as it affects core input handling mechanisms that are fundamental to graphical user interfaces, making it a prime target for exploitation in environments where remote access is possible. The affected functions span across various input device control operations including device configuration, event handling, pointer manipulation, and device property management, indicating a systemic weakness in input validation throughout the XInput extension subsystem.
The technical nature of this vulnerability manifests as out-of-bounds read or write operations that occur when the X server processes specially crafted length or index values in the targeted functions. These functions operate within the X11 protocol's extension mechanism, specifically handling input device interactions through the XInput extension which was introduced to provide enhanced input device support beyond basic X11 capabilities. When an authenticated user sends malicious requests containing invalid length or index parameters, the server fails to properly validate these inputs before processing them, leading to memory corruption that can result in either denial of service conditions or potential code execution. The flaw operates at the protocol level where client applications communicate with the X server, making it possible for attackers to exploit the vulnerability without requiring physical access to the system.
The operational impact of this vulnerability extends beyond simple service disruption, as it potentially enables arbitrary code execution on affected systems. This capability arises from the out-of-bounds memory access patterns that can be manipulated to overwrite critical memory locations or inject malicious code into the X server process. The vulnerability affects a comprehensive set of XInput extension functions, covering everything from basic device control operations to complex event handling and pointer manipulation. Systems running affected X server versions are particularly vulnerable when they allow remote authenticated access, such as in networked environments where X11 forwarding is enabled or when systems are accessed through remote desktop protocols that utilize X11. The widespread use of X11 in Unix-like operating systems and Linux distributions makes this vulnerability particularly dangerous as it could affect a large number of systems across various deployment scenarios.
Mitigation strategies for CVE-2014-8095 primarily focus on upgrading to X.Org Server version 1.16.3 or later, which includes proper input validation fixes for all the affected functions. Administrators should also implement network segmentation and access controls to limit exposure to authenticated users who could potentially exploit this vulnerability. Additional defensive measures include monitoring X server logs for suspicious activity patterns and implementing proper network firewall rules to restrict X11 traffic to trusted networks only. The vulnerability aligns with CWE-129: Improper Validation of Array Index, which specifically addresses issues where array indices are not properly validated, leading to out-of-bounds memory access. From an ATT&CK framework perspective, this vulnerability maps to T1059.007: Command and Scripting Interpreter: Python, and T1203: Exploitation for Client Execution, as it enables an attacker to execute arbitrary code on the target system through legitimate input processing mechanisms. Organizations should also consider implementing intrusion detection systems that can identify patterns of exploitation attempts targeting X11 protocol extensions and ensure regular security updates are applied to maintain system integrity against such vulnerabilities.