CVE-2021-40264 in Freeimage
Summary
by MITRE • 08/22/2023
NULL pointer dereference vulnerability in FreeImage before 1.18.0 via the FreeImage_CloneTag function inFreeImageTag.cpp.
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Analysis
by VulDB Data Team • 09/16/2023
The CVE-2021-40264 vulnerability represents a critical null pointer dereference flaw discovered in the FreeImage library version 1.18.0 and earlier. This vulnerability specifically affects the FreeImage_CloneTag function located within the FreeImageTag.cpp source file, making it a fundamental issue within the library's tag handling mechanisms. FreeImage is a widely-used open-source library for reading and writing various image formats, including bmp, gif, jpeg, png, and tiff, which makes this vulnerability particularly concerning given its potential impact across numerous applications and systems that depend on this library for image processing capabilities. The vulnerability stems from inadequate input validation and error handling within the tag cloning functionality, where the software fails to properly check for null pointers before attempting to dereference them during the cloning process.
The technical exploitation of this vulnerability occurs when an attacker provides malformed or specially crafted image files that trigger the FreeImage_CloneTag function with invalid tag data structures. During normal operation, the function should validate that tag pointers are not null before attempting to access their contents. However, in vulnerable versions, this validation is either absent or insufficient, leading to a null pointer dereference when the code attempts to access memory locations that have not been properly allocated or initialized. This condition typically results in an application crash or segmentation fault, effectively causing a denial of service condition that can be exploited by malicious actors to disrupt system availability. The vulnerability is classified as a CWE-476 Null Pointer Dereference under the Common Weakness Enumeration framework, which specifically addresses the scenario where software attempts to access memory through a pointer that has not been properly initialized to point to a valid memory location.
The operational impact of CVE-2021-40264 extends beyond simple denial of service scenarios, as it can be leveraged in more sophisticated attack vectors within the MITRE ATT&CK framework's execution and privilege escalation categories. Applications that utilize FreeImage for image processing, including web servers, image editing software, and content management systems, become vulnerable to remote exploitation when processing untrusted image data. The vulnerability can be particularly dangerous in server environments where automated image processing is common, as attackers could craft malicious image files to cause service interruptions across multiple systems simultaneously. Additionally, the vulnerability may be exploited as part of a broader attack chain where initial access is gained through other means, and the null pointer dereference serves as a reliable method for maintaining persistence or escalating privileges within compromised systems. The widespread adoption of FreeImage across various software platforms means that a single vulnerable library instance can potentially affect numerous applications, making this vulnerability a significant concern for system administrators and security teams responsible for maintaining software supply chain integrity.
Mitigation strategies for CVE-2021-40264 primarily focus on immediate software updates to version 1.18.0 or later, where the null pointer dereference issue has been addressed through proper input validation and error handling mechanisms. Organizations should conduct comprehensive vulnerability assessments to identify all systems and applications that utilize vulnerable versions of FreeImage, particularly those handling user-uploaded content or processing external image data. The implementation of input sanitization measures, including strict validation of image file formats and content, can provide additional defense-in-depth layers against exploitation attempts. Security teams should also consider implementing network segmentation and access controls to limit the potential impact of successful exploitation attempts, while monitoring for unusual application behavior or crash patterns that may indicate attempted exploitation of this vulnerability. Regular security updates and patch management procedures should be reinforced to ensure that all dependencies, including open-source libraries like FreeImage, remain current with the latest security fixes and improvements.