CVE-2026-33721 Details
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.
A heap-buffer-overflow vulnerability has been identified in MapServer versions 4.2 prior to 8.6.1. This issue arises in the Styled Layer Descriptor (SLD) parser, specifically within the 'Categorize' Threshold handling. The vulnerability allows a remote, unauthenticated attacker to crash the MapServer process by sending a specially crafted SLD that contains more than 100 Threshold elements within a ColorMap/Categorize structure. This scenario is commonly encountered via WMS GetMap requests that include SLD_BODY.
Users are advised to upgrade to MapServer version 8.6.1, which addresses this vulnerability. The release can be downloaded from the MapServer GitHub repository.
Metrics
CVSS 4.0 Severity and Vector Strings:
No CVSS 4.0 data is available for this CVE.
CVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
CISA-ADP
Assessed Mar 30, 2026References to Advisories, Solutions, and Tools
By selecting these links, you will be leaving this site. These are references gathered from the official CVE record and are not endorsed by Volerion.
| URL | Source(s) | Tag(s) |
|---|---|---|
| https://lists.debian.org/debian-lts-announce/2026/04/msg00017.html | CVE | |
| https://github.com/MapServer/MapServer/releases/tag/rel-8-6-1 | [email protected] | ProductRelease Notes |
| https://github.com/MapServer/MapServer/security/advisories/GHSA-cv4m-mr84-fgjp | [email protected] | ExploitMitigationVendor Advisory |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-787 | Out-of-bounds Write | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| osgeo mapserver | >= 4.2.0, < 8.6.1 |
CPE
Remediation
| |
Change History
5 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jun 17, 2026 | CVE Modified | [email protected] |
| Jun 17, 2026 | CVE Modified | CISA-ADP |
| Apr 17, 2026 | CVE Modified | CVE |
| Apr 1, 2026 | Initial Analysis | [email protected] |
| Mar 27, 2026 | New CVE Received | [email protected] |