CVE-2025-15537 Overview
A heap-based buffer overflow vulnerability has been identified in Mapnik, an open-source toolkit for developing mapping applications. This security flaw affects the mapnik::dbf_file::string_value function within the file plugins/input/shape/dbfile.cpp. When exploited, an attacker with local access can manipulate data to trigger a heap-based buffer overflow, potentially leading to memory corruption, application crashes, or arbitrary code execution.
Critical Impact
Local attackers can exploit this heap-based buffer overflow to corrupt memory, crash the application, or potentially execute arbitrary code when processing malformed shapefile DBF data.
Affected Products
- Mapnik up to version 4.2.0
- Applications utilizing Mapnik's shapefile input plugin
- Systems processing untrusted shapefile data through Mapnik
Discovery Timeline
- 2026-01-18 - CVE CVE-2025-15537 published to NVD
- 2026-01-20 - Last updated in NVD database
Technical Details for CVE-2025-15537
Vulnerability Analysis
This vulnerability is classified as a heap-based buffer overflow (CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer). The flaw resides in the shapefile input plugin, specifically within the DBF file parsing functionality. DBF (dBASE) files are commonly used alongside shapefiles to store attribute data for geographic features.
The vulnerable function mapnik::dbf_file::string_value fails to properly validate buffer boundaries when processing string values from DBF files. When a specially crafted DBF file contains malformed string field data, the function may write beyond the allocated heap buffer, leading to heap corruption.
Since the attack vector is local, an attacker would need to convince a user or automated system to process a malicious shapefile, or have direct access to provide input files to a Mapnik-based application.
Root Cause
The root cause of this vulnerability stems from insufficient bounds checking in the string_value function within plugins/input/shape/dbfile.cpp. When parsing string fields from DBF files, the code does not adequately verify that the data being read fits within the allocated buffer space. This allows malformed input to overflow heap memory, potentially overwriting adjacent heap structures or application data.
Attack Vector
The attack requires local access to the target system. An attacker must craft a malicious shapefile with a specially constructed DBF component containing oversized or malformed string field data. When a Mapnik-based application attempts to read and process this file, the heap overflow is triggered.
The vulnerability has been publicly disclosed with proof-of-concept materials available through the GitHub PoC Repository. The project maintainers were notified through GitHub Issue #4543, but have not yet responded.
Detection Methods for CVE-2025-15537
Indicators of Compromise
- Unexpected crashes or segmentation faults in Mapnik-based applications when processing shapefile data
- Memory corruption errors or heap corruption warnings in application logs
- Abnormal memory usage patterns when loading DBF files
- Core dumps indicating heap buffer overflow in mapnik::dbf_file::string_value
Detection Strategies
- Monitor for application crashes with stack traces pointing to plugins/input/shape/dbfile.cpp
- Implement file integrity monitoring on shapefile directories to detect suspicious or newly introduced files
- Use AddressSanitizer (ASAN) or similar memory debugging tools during development and testing
- Deploy endpoint detection solutions capable of identifying heap exploitation attempts
Monitoring Recommendations
- Enable verbose logging for Mapnik-based applications to capture file processing errors
- Monitor system logs for repeated crashes or memory-related errors in mapping applications
- Implement alerting for unusual file access patterns to shapefile directories
- Review application audit logs for attempts to load files from untrusted sources
How to Mitigate CVE-2025-15537
Immediate Actions Required
- Restrict local access to systems running Mapnik-based applications
- Validate and sanitize all shapefile inputs before processing
- Implement strict file source verification to prevent processing of untrusted shapefiles
- Consider temporarily disabling the shapefile input plugin if not required for operations
Patch Information
As of the last update on 2026-01-20, no official patch has been released by the Mapnik project. The vulnerability was reported through GitHub Issue #4543, but the project has not yet responded. Users should monitor the official Mapnik repository for security updates and apply patches immediately when available.
For additional vulnerability context and tracking, refer to VulDB #341709.
Workarounds
- Avoid processing shapefiles from untrusted or unverified sources
- Implement input validation to check DBF file structure and field sizes before passing to Mapnik
- Run Mapnik-based applications with reduced privileges to limit the impact of potential exploitation
- Consider using application sandboxing or containerization to isolate Mapnik processing environments
- Implement file type and size restrictions on uploaded or processed shapefiles
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
