CVE-2016-8685 in potrace
Summary
by MITRE
The findnext function in decompose.c in potrace 1.13 allows remote attackers to cause a denial of service (invalid memory access and crash) via a crafted BMP image.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 08/08/2020
The vulnerability identified as CVE-2016-8685 affects the potrace 1.13 library, specifically within the findnext function located in decompose.c. This issue represents a classic buffer over-read condition that occurs during the processing of bitmap images, particularly when handling malformed or crafted BMP files. The potrace library is widely used for tracing bitmap images into vector graphics, making this vulnerability potentially impactful across numerous applications that rely on its functionality for image processing and conversion tasks.
The technical flaw manifests when the findnext function processes a specially crafted BMP image that contains malformed data structures or unexpected byte sequences. During the decompression and analysis phase of the image processing pipeline, the function attempts to access memory locations beyond the allocated buffer boundaries, resulting in invalid memory access patterns. This memory corruption leads to immediate program termination and system crash, effectively creating a denial of service condition that can be exploited remotely by attackers who can submit malicious BMP files to systems running vulnerable versions of potrace.
From an operational perspective, this vulnerability presents significant risk to systems that process user-uploaded or externally sourced bitmap images, particularly web applications, image processing services, and document management systems. The remote exploitation capability means that attackers can trigger the denial of service condition without requiring local access to the target system, making it particularly dangerous in networked environments. The vulnerability affects not only direct applications using potrace but also any software that incorporates the library, creating a wide attack surface that extends across multiple software ecosystems.
The impact of this vulnerability aligns with CWE-125, which describes out-of-bounds read conditions that can lead to memory corruption and system instability. From an adversarial perspective, this vulnerability maps to attack techniques documented in the MITRE ATT&CK framework under the T1499 category for network denial of service, where attackers can leverage memory corruption vulnerabilities to disrupt service availability. The vulnerability demonstrates the critical importance of proper input validation and memory boundary checking in image processing libraries, particularly those handling untrusted data from external sources.
Organizations should implement immediate mitigations including upgrading to potrace versions that address this vulnerability, typically versions 1.14 and later. Additionally, input validation measures should be implemented at the application level to sanitize BMP file inputs before processing, including size restrictions and format verification. Network-level protections such as content filtering and sandboxing mechanisms can provide additional defense-in-depth layers. Regular security assessments and vulnerability scanning should be conducted to identify other potential instances of similar memory corruption issues within the software supply chain, particularly in image processing and graphics manipulation libraries that are commonly integrated into enterprise applications.