CVE-2009-5063 in libpng
Summary
by MITRE
Memory leak in the embedded_profile_len function in pngwutil.c in libpng before 1.2.39beta5 allows context-dependent attackers to cause a denial of service (memory leak or segmentation fault) via a JPEG image containing an iCCP chunk with a negative embedded profile length. NOTE: this is due to an incomplete fix for CVE-2006-7244.
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Analysis
by VulDB Data Team • 11/18/2021
The vulnerability described in CVE-2009-5063 represents a memory management flaw within the libpng library that affects versions prior to 1.2.39beta5. This issue specifically targets the embedded_profile_len function located in the pngwutil.c source file, which handles the processing of iCCP chunks in JPEG images. The flaw manifests when the library encounters a malformed iCCP chunk containing a negative embedded profile length value, creating a condition where the application fails to properly manage memory allocation and deallocation processes. The vulnerability is particularly concerning because it builds upon an incomplete fix for CVE-2006-7244, indicating a persistent weakness in the library's handling of profile length validation mechanisms.
The technical implementation of this vulnerability stems from inadequate input validation within the embedded_profile_len function, which does not properly verify the bounds of the embedded profile length parameter before proceeding with memory allocation operations. When a malicious JPEG image contains an iCCP chunk with a negative length value, the function attempts to allocate memory based on this invalid parameter, leading to unpredictable behavior in the memory management system. This condition can result in either a memory leak where allocated memory is not properly freed, or in more severe cases, a segmentation fault that crashes the application process. The context-dependent nature of this vulnerability means that exploitation requires a specific scenario involving the processing of crafted JPEG images, making it less likely to be exploited in the wild but still posing significant risks to applications that handle untrusted image data.
From an operational impact perspective, this vulnerability directly affects any system or application that relies on libpng for image processing, particularly those handling user-uploaded content or processing images from untrusted sources. The denial of service conditions can disrupt services ranging from web applications that process image uploads to image processing pipelines in multimedia applications. Security professionals should note that this vulnerability aligns with CWE-457: Use of Uninitialized Variable, as the negative length value creates an uninitialized or improperly initialized memory allocation scenario. The attack vector specifically maps to ATT&CK technique T1203: Exploitation for Client Execution, where adversaries leverage application vulnerabilities to cause service disruption through memory management flaws. Applications using libpng versions prior to 1.2.39beta5 are particularly vulnerable during image parsing operations, with the potential for cascading failures in systems that do not implement proper error handling for malformed image data.
The recommended mitigation strategy involves immediate upgrading of libpng installations to version 1.2.39beta5 or later, which contains the complete fix for both CVE-2006-7244 and CVE-2009-5063. Organizations should also implement defensive programming practices such as input validation for all image processing operations and consider deploying additional layers of protection including sandboxing image processing components and implementing proper resource monitoring to detect potential memory leaks. System administrators should conduct comprehensive vulnerability assessments to identify all applications using affected libpng versions and ensure that proper patch management procedures are in place to prevent similar issues from arising in the future. The fix addresses the root cause by implementing proper bounds checking and error handling for embedded profile length parameters, preventing the propagation of negative values that could lead to memory allocation failures.