CVE-2016-8695 in potrace
Summary
by MITRE
The bm_readbody_bmp function in bitmap_io.c in potrace before 1.13 allows remote attackers to cause a denial of service (NULL pointer dereference and crash) via a crafted BMP image, a different vulnerability than CVE-2016-8694 and CVE-2016-8696.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 08/08/2020
The vulnerability identified as CVE-2016-8695 affects the potrace library version 1.12 and earlier, specifically within the bitmap_io.c file in the bm_readbody_bmp function. This issue represents a denial of service vulnerability that can be exploited by remote attackers through the careful crafting of BMP image files. The flaw manifests as a NULL pointer dereference that ultimately leads to application crash, effectively rendering the targeted system unavailable to legitimate users. The vulnerability operates independently from other related issues such as CVE-2016-8694 and CVE-2016-8696, indicating a distinct code path that requires separate remediation efforts.
The technical implementation of this vulnerability stems from inadequate input validation within the bitmap image parsing routine. When the bm_readbody_bmp function processes malformed BMP files, it fails to properly handle certain edge cases in the image header structures or pixel data arrangements. This deficiency allows attackers to construct specifically formatted BMP images that, when processed by potrace, trigger a NULL pointer dereference during the bitmap reading operation. The vulnerability falls under CWE-476 which specifically addresses NULL pointer dereference conditions in software implementations. The function's inability to properly validate image metadata and pixel format specifications creates a pathway for malicious input to bypass normal execution flow and cause unexpected program termination.
From an operational perspective, this vulnerability presents significant risk to systems that process user-uploaded bitmap images or integrate potrace functionality for vector graphics conversion. The remote exploit nature means that attackers can trigger the denial of service condition without requiring local access or elevated privileges, making it particularly dangerous in web applications or services that accept image uploads. The impact extends beyond simple service disruption as it can be leveraged in broader attack campaigns targeting availability of critical infrastructure or web applications that rely on image processing capabilities. This vulnerability directly impacts the availability aspect of the CIA triad and can be classified under the ATT&CK technique T1499.100 which addresses network denial of service attacks through exploitation of software vulnerabilities.
Mitigation strategies for CVE-2016-8695 primarily involve upgrading to potrace version 1.13 or later where the vulnerability has been addressed through improved input validation and error handling mechanisms. System administrators should also implement additional defensive measures such as image validation routines that check file headers and metadata before processing, implementing strict file format validation, and deploying sandboxing techniques for image processing operations. The fix typically involves adding proper NULL pointer checks and robust error handling within the bm_readbody_bmp function to gracefully handle malformed input rather than allowing the application to crash. Organizations should also consider implementing network-level protections such as rate limiting and content filtering to reduce the impact of potential exploitation attempts. Additionally, regular security audits of third-party libraries and dependencies should be conducted to identify and remediate similar vulnerabilities before they can be exploited by malicious actors.