CVE-2026-33721 MEDIUM

CVE-2026-33721: MapServer has heap buffer overflow in SLD `Categorize` Threshold parsing

Vendor Mapserver
Product MapServer
Weakness CWE-787
Published March 27, 2026
Last update April 17, 2026
View on NVD All CVEs

CVSS base score

5.3/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Confidentiality None
Integrity None

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

March 27, 2026 CVE published
April 17, 2026 Record updated