CVE-2014-2497 in PHP
Summary
by MITRE
The gdImageCreateFromXpm function in gdxpm.c in libgd, as used in PHP 5.4.26 and earlier, allows remote attackers to cause a denial of service (NULL pointer dereference and application crash) via a crafted color table in an XPM file.
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Analysis
by VulDB Data Team • 05/08/2026
The vulnerability identified as CVE-2014-2497 resides within the libgd library's gdImageCreateFromXpm function located in gdxpm.c, representing a critical denial of service weakness that affects PHP versions up to 5.4.26. This flaw manifests when the function processes specially crafted XPM image files containing malformed color table entries, leading to a NULL pointer dereference that ultimately crashes the application. The issue stems from inadequate input validation and error handling within the image parsing routine, where the software fails to properly validate color table entries before attempting to access memory locations that may not be properly initialized or allocated.
The technical exploitation of this vulnerability occurs when an attacker uploads or processes an XPM file containing malformed color table data that causes the gdImageCreateFromXpm function to attempt to dereference a NULL pointer during the image creation process. This specific flaw aligns with CWE-476 which categorizes NULL pointer dereferences as a common software weakness, and represents a classic example of insufficient error handling in image processing libraries. The vulnerability operates at the intersection of image parsing and memory management, where improper validation of user-supplied input leads to application instability and potential service disruption.
From an operational perspective, this vulnerability poses significant risks to web applications that utilize PHP's image processing capabilities, particularly those that accept user-uploaded images or process external image sources without proper sanitization. Attackers can leverage this weakness to perform denial of service attacks against web servers running affected PHP versions, potentially causing widespread service interruption and resource exhaustion. The impact extends beyond simple application crashes to encompass broader system availability concerns, as the vulnerability can be exploited through various attack vectors including file upload handlers, image processing APIs, and content management systems that utilize PHP's GD library for image manipulation tasks.
The mitigation strategies for CVE-2014-2497 primarily focus on immediate patching of affected PHP installations to versions that include the necessary fixes for the libgd library. Organizations should implement comprehensive input validation and sanitization measures for all image uploads, including MIME type checking, file format validation, and size restrictions to prevent exploitation. Additionally, deployment of web application firewalls and intrusion detection systems can help identify and block malicious XPM file submissions. Security teams should also consider implementing sandboxed image processing environments and regular vulnerability assessments to identify similar weaknesses in image processing libraries. The ATT&CK framework categorizes this vulnerability under privilege escalation and denial of service tactics, with the specific technique mapping to the use of malformed input to cause application instability. Organizations must prioritize updating their PHP installations and implementing robust input validation as primary defensive measures against this and similar image parsing vulnerabilities.