CVE-2013-1998 in libXi
Summary
by MITRE
Multiple buffer overflows in X.org libXi 1.7.1 and earlier allow X servers to cause a denial of service (crash) and possibly execute arbitrary code via crafted length or index values to the (1) XGetDeviceButtonMapping, (2) XIPassiveGrabDevice, and (3) XQueryDeviceState functions.
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Analysis
by VulDB Data Team • 05/14/2021
The vulnerability identified as CVE-2013-1998 represents a critical security flaw within the X.org libXi library version 1.7.1 and earlier, affecting the broader X Window System ecosystem. This issue stems from inadequate input validation mechanisms within three core functions that handle device interaction protocols. The affected functions include XGetDeviceButtonMapping, XIPassiveGrabDevice, and XQueryDeviceState, which are integral components of the X Input extension responsible for managing various input devices within graphical environments. These functions operate within the X server context and process requests from client applications, making them prime targets for exploitation through malformed input parameters.
The technical implementation of this vulnerability manifests through buffer overflow conditions that occur when the X server processes crafted length or index values passed to the vulnerable functions. When these functions receive malformed input parameters, they fail to properly validate the boundaries of memory allocations, leading to memory corruption that can result in stack or heap overflows. The vulnerability specifically targets the input validation mechanisms within the libXi library, which serves as a critical middleware component between X client applications and the X server. This flaw operates at the protocol level, where the X server's handling of device state queries and input device mappings creates opportunities for attackers to inject malicious data that exceeds allocated buffer boundaries.
The operational impact of this vulnerability extends beyond simple denial of service conditions, presenting potential for arbitrary code execution within the context of the X server process. When successfully exploited, these buffer overflows can cause the X server to crash, resulting in complete system graphical interface disruption and potentially allowing attackers to execute malicious code with the privileges of the X server process. The severity classification of this vulnerability aligns with CWE-121, which addresses stack-based buffer overflow conditions, and CWE-122, which covers heap-based buffer overflow scenarios. The attack surface is particularly concerning given that X servers typically run with elevated privileges and have direct access to hardware resources, making successful exploitation particularly damaging to system integrity and availability.
From an operational perspective, this vulnerability affects systems utilizing X Window System implementations where libXi version 1.7.1 or earlier is installed, encompassing various Unix-like operating systems including Linux distributions and BSD variants. The attack vector requires local or network access to an X server that accepts client connections, making it particularly relevant in multi-user environments or systems with X11 forwarding enabled. Mitigation strategies should focus on immediate patching of the libXi library to versions containing proper input validation and bounds checking mechanisms. System administrators should also consider implementing network segmentation to limit X server access, disabling unnecessary X11 forwarding, and monitoring for anomalous X server behavior that might indicate exploitation attempts. The vulnerability demonstrates the importance of proper input validation in graphical system components and highlights the need for comprehensive security testing of middleware libraries that operate with elevated privileges in graphical environments.