CVE-2014-0333 in libpng
Summary
by MITRE
The png_push_read_chunk function in pngpread.c in the progressive decoder in libpng 1.6.x through 1.6.9 allows remote attackers to cause a denial of service (infinite loop and CPU consumption) via an IDAT chunk with a length of zero.
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Analysis
by VulDB Data Team • 04/12/2025
The vulnerability identified as CVE-2014-0333 represents a critical denial of service flaw within the libpng library's progressive decoder implementation. This issue specifically affects versions 1.6.x through 1.6.9 of the widely-used PNG image processing library. The vulnerability stems from improper handling of IDAT chunks during the progressive decoding process, creating a condition where maliciously crafted PNG files can trigger infinite loop scenarios that consume excessive CPU resources. The affected png_push_read_chunk function in pngpread.c demonstrates a failure to properly validate chunk length parameters, particularly when encountering IDAT chunks with zero length values.
The technical exploitation of this vulnerability occurs through the progressive PNG decoder's handling of image data chunks. When the decoder encounters an IDAT chunk with a length of zero, the parsing logic fails to properly terminate the processing loop, resulting in an infinite iteration that consumes CPU cycles indefinitely. This behavior represents a classic denial of service condition where legitimate system resources become unavailable due to malicious input. The vulnerability is particularly concerning because libpng is extensively used across numerous applications and operating systems, making the potential attack surface vast. The flaw demonstrates poor input validation practices and inadequate boundary checking within the image parsing pipeline.
The operational impact of CVE-2014-0333 extends beyond simple resource exhaustion, as it can affect any system that processes PNG images through the vulnerable libpng library. Attackers can exploit this vulnerability by delivering specially crafted PNG files to web applications, email clients, or any software that utilizes libpng for image processing. The infinite loop consumes CPU resources at maximum capacity, potentially leading to system instability, application crashes, or complete service unavailability. This vulnerability aligns with CWE-835, which describes the weakness of infinite loops or iterations without proper exit conditions, and represents a clear violation of secure coding practices that should prevent such resource consumption attacks.
Mitigation strategies for this vulnerability involve immediate patching of affected libpng versions to 1.6.10 or later, where the issue has been resolved through proper validation of chunk lengths. System administrators should also implement input validation measures at network boundaries, filtering PNG files based on chunk size parameters to prevent malformed images from reaching vulnerable applications. Additionally, applications using libpng should implement timeout mechanisms and resource limits when processing image files to prevent exploitation. The remediation process should include comprehensive testing to ensure that patched versions properly handle edge cases while maintaining compatibility with legitimate PNG files. This vulnerability underscores the importance of robust input validation and proper error handling in image processing libraries, as outlined in various security frameworks including those addressing secure coding practices and application security controls.