CVE-2017-7263 in potrace
Summary
by MITRE
The bm_readbody_bmp function in bitmap_io.c in Potrace 1.14 allows remote attackers to cause a denial of service (heap-based buffer over-read and application crash) or possibly have unspecified other impact via a crafted BMP image. NOTE: this vulnerability exists because of an incomplete fix for CVE-2016-8698.
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Analysis
by VulDB Data Team • 09/14/2020
The vulnerability identified as CVE-2017-7263 affects the Potrace 1.14 library, specifically within the bm_readbody_bmp function located in bitmap_io.c. This issue represents a regression that emerged from an incomplete remediation of a previous vulnerability, CVE-2016-8698, which highlights the critical importance of thorough vulnerability patching and validation. The flaw manifests as a heap-based buffer over-read condition that occurs when processing maliciously crafted BMP image files, creating a significant risk for systems that utilize Potrace for bitmap processing operations.
The technical nature of this vulnerability stems from inadequate input validation and boundary checking within the bitmap reading functionality. When Potrace encounters a specially crafted BMP image, the bm_readbody_bmp function fails to properly validate the image dimensions and data structure, leading to memory access violations. This buffer over-read condition allows attackers to manipulate memory layout and potentially trigger application crashes or more severe system instability. The vulnerability operates at the memory management level, where the application attempts to read beyond allocated heap memory boundaries, creating unpredictable behavior that can be exploited for denial of service attacks.
From an operational impact perspective, this vulnerability poses substantial risks to systems that process user-uploaded or externally sourced bitmap images through Potrace. The remote attack vector means that adversaries can exploit this flaw without requiring local system access, making it particularly dangerous in web applications, file processing services, or any environment where BMP files are handled. The potential for unspecified other impacts suggests that beyond simple denial of service, attackers might be able to execute arbitrary code or manipulate application state, though the primary risk remains system instability and service disruption. This vulnerability affects the broader ecosystem of applications that depend on Potrace for vectorization of bitmap images, including graphic design software, document conversion tools, and automated image processing pipelines.
The remediation approach for CVE-2017-7263 requires implementing proper input validation and boundary checking mechanisms within the bitmap reading code. Security practitioners should ensure that all image dimensions are thoroughly validated before memory allocation occurs, and that buffer access operations are strictly bounded by allocated memory limits. The complete fix must address the root cause identified in CVE-2016-8698 while ensuring that no regressions are introduced. Organizations should prioritize updating to Potrace versions that contain proper fixes for both vulnerabilities, and implement additional input sanitization measures at application layers that process BMP files. This vulnerability aligns with CWE-125, which describes out-of-bounds read conditions, and may also relate to ATT&CK techniques involving privilege escalation and denial of service through memory corruption. System administrators should monitor for exploitation attempts and consider implementing network-based intrusion detection rules targeting known malicious BMP file patterns to detect and prevent exploitation attempts.