CVE-2005-2495 in XFree86
Summary
by MITRE
Multiple integer overflows in XFree86 before 4.3.0 allow user-assisted attackers to execute arbitrary code via a crafted pixmap image.
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Analysis
by VulDB Data Team • 06/30/2025
The vulnerability identified as CVE-2005-2495 represents a critical security flaw within the XFree86 graphics subsystem that affected versions prior to 4.3.0. This issue manifests through multiple integer overflow conditions that occur during the processing of pixmap images, creating a pathway for malicious actors to potentially execute arbitrary code on affected systems. The vulnerability specifically targets the memory management and image handling components of the X Window System implementation, which forms the foundation for graphical user interfaces across numerous unix-like operating systems.
The technical implementation of this vulnerability stems from inadequate input validation and arithmetic overflow handling within the pixmap image processing routines. When XFree86 encounters a crafted pixmap image with maliciously constructed dimensions or metadata, the integer variables used to calculate memory allocation sizes can overflow, resulting in insufficient memory allocation or incorrect memory boundaries. This overflow condition creates memory corruption that can be exploited to overwrite critical program memory locations, potentially allowing attackers to inject and execute malicious code with the privileges of the running X server process. The vulnerability operates under the common weakness enumeration CWE-190 which specifically addresses integer overflow conditions, and aligns with ATT&CK technique T1068 which covers exploit for privilege escalation through local system vulnerabilities.
The operational impact of CVE-2005-2495 extends beyond simple code execution capabilities, as it can be leveraged to compromise entire graphical environments and potentially escalate privileges within the system. Attackers can craft malicious pixmap files that, when processed by the XFree86 server, trigger the integer overflow conditions and lead to arbitrary code execution. This vulnerability is particularly dangerous because it operates at the graphical subsystem level, meaning that exploitation can occur through various attack vectors including email attachments, web downloads, or file transfers that involve image processing. The user-assisted nature of the attack means that victims must interact with the malicious pixmap file, typically by opening it in an image viewer or application that uses XFree86 for rendering, but the actual exploitation occurs within the graphics subsystem rather than requiring direct system-level access.
Mitigation strategies for this vulnerability involve immediate upgrading to XFree86 version 4.3.0 or later, which contains patches specifically addressing the integer overflow conditions in pixmap processing. System administrators should also implement additional security measures such as restricting user access to image processing applications, implementing strict file type validation for image files, and monitoring for unusual memory allocation patterns that might indicate exploitation attempts. The patch for this vulnerability demonstrates the importance of proper integer overflow handling in security-critical code, particularly in graphics libraries that process untrusted input data. Organizations should also consider implementing network segmentation to limit the potential impact of successful exploitation, as the vulnerability affects the core X Window System that many applications depend upon for graphical display functionality. This vulnerability serves as a reminder of the critical importance of input validation and proper memory management in preventing remote code execution through graphical subsystems, and aligns with security best practices outlined in both CWE guidelines and MITRE ATT&CK framework for defending against privilege escalation attacks.