CVE-2026-33721CWE-787

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

Medium · published March 27, 2026

CVSS v3.1
5.3
EPSS
1%
Percentile
56.7
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
5.3 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
CVSS v4.0
Not supplied
EPSS
0.00816 · 56.7th percentile
Weakness
CWE-787 · Out-of-bounds Write
Published
2026-03-27T00:15Z
EPSS history
Timeline
  • 27 MAR 00:15Z
    MapServer has heap buffer overflow in SLD `Categorize` Threshold parsing
    cvelistv5