CVE-2026-33721

MEDIUM

MapServer has heap buffer overflow in SLD `Categorize` Threshold parsing

Title source: cna
STIX 2.1

Description

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.

References (3)

Core 3

Scores

CVSS v3 5.3
EPSS 0.0065
EPSS Percentile 46.0%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

CISA SSVC

Vulnrichment
Exploitation poc
Automatable yes
Technical Impact partial

Details

CWE
CWE-787
Status published
Products (2)
MapServer/MapServer >= 4.2, < 8.6.1
osgeo/mapserver 4.2.0 - 8.6.1
Published Mar 27, 2026
Tracked Since Mar 27, 2026