HIGHVulnerability
Verified
Global

NVD HIGH: CVE-2026-33721 — MapServer is a system for developing web-based GIS applications. Starting in ver...

Friday, March 27, 2026 at 01:16 AM UTC·Source: NIST NVD

Updated: Thursday, April 2, 2026 at 05:46 PM UTC

Executive Summary

MapServer is a system for developing web-based GIS applications. Starting in version 4.2 and prior to version 8.6.1, a heap-buffer-overflow write in MapServer’s SLD (Styled Layer Descriptor) parser lets a remote, unauthenticated attacker crash the MapServer process by sending a crafted SLD with more than 100 Threshold elements inside a ColorMap/Categorize structure (commonly reachable via WMS GetM

Analysis

MapServer is a system for developing web-based GIS applications. Starting in version 4.2 and prior to version 8.6.1, a heap-buffer-overflow write in MapServer’s SLD (Styled Layer Descriptor) parser lets a remote, unauthenticated attacker crash the MapServer process by sending a crafted SLD with more than 100 Threshold elements inside a ColorMap/Categorize structure (commonly reachable via WMS GetMap with SLD_BODY). Version 8.6.1 patches the issue. CVSS Score: 5.3. Published: 2026-03-27T01:16:19.670.

Indicators of Compromise (1)

CVE (1)
CVE-2026-33721
NVDMITRE CVE
Source Attribution

Originally published by NIST NVD on Mar 27, 2026. Verified by: NIST.

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