CVE-2018-14550 in libpng
Summary
by MITRE
An issue has been found in third-party PNM decoding associated with libpng 1.6.35. It is a stack-based buffer overflow in the function get_token in pnm2png.c in pnm2png.
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Analysis
by VulDB Data Team • 10/24/2023
The vulnerability identified as CVE-2018-14550 represents a critical stack-based buffer overflow affecting the libpng library version 1.6.35 and related third-party PNM decoding components. This flaw manifests within the pnm2png utility's function get_token located in the pnm2png.c source file, creating a significant security risk that can be exploited by malicious actors. The issue arises from inadequate input validation and bounds checking during the processing of PNM (Portable AnyMap) image format data, which is commonly used for storing raster graphics in various applications and systems.
The technical exploitation of this vulnerability occurs when the get_token function processes malformed PNM files without proper boundary checks, allowing an attacker to write data beyond the allocated stack buffer space. This stack overflow condition can be leveraged to overwrite adjacent memory locations, potentially leading to arbitrary code execution or application crashes. The vulnerability is particularly concerning because PNM format support is integrated into numerous image processing applications, graphics tools, and web servers that utilize libpng for image handling, creating widespread potential impact across different software ecosystems. The flaw demonstrates a classic stack buffer overflow pattern that aligns with CWE-121, which specifically addresses stack-based buffer overflow conditions where insufficient bounds checking allows data to overwrite adjacent stack memory.
From an operational standpoint, this vulnerability presents substantial risk to systems that process untrusted image data, particularly web applications, content management systems, and image processing pipelines that may be vulnerable to remote code execution attacks. The exploitation can occur through simple file upload mechanisms or when applications automatically process PNM formatted images from external sources. The impact extends beyond individual applications to potentially compromise entire systems, as successful exploitation could allow attackers to execute malicious code with the privileges of the affected application. This vulnerability also aligns with ATT&CK technique T1203, which covers exploitation of software vulnerabilities through buffer overflow attacks, making it a significant concern for organizations maintaining robust cybersecurity defenses.
Mitigation strategies for CVE-2018-14550 should prioritize immediate patching of all affected libpng installations to version 1.6.36 or later, which contains the necessary fixes for the buffer overflow condition. Organizations should implement comprehensive input validation and sanitization for all image file processing, particularly when handling PNM format files from untrusted sources. Network segmentation and access controls should be strengthened to limit exposure of systems that process image data, while regular security assessments should be conducted to identify and remediate similar vulnerabilities in other third-party libraries. Additionally, application developers should adopt secure coding practices including bounds checking, stack canaries, and address space layout randomization to reduce the exploitability of similar buffer overflow conditions in their software implementations.