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TI-2026-26100 Aliases CVE-2026-33721

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

Priority HIGH 72CWE-787Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Denial of service
Confidentiality · integrity · availability
None · None · High
Fix status
Fixed

Attack profile from CVSS 3.1 · NVD. Fix status from CNA. Impact type from CWE-787 and the CVSS impact.

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 GetMap with SLD_BODY). Version 8.6.1 patches the issue.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.0122 68th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Fixed MapServer (MapServer): 8.6.1

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
OSGeoMapServer4.2 to before 8.6.18.6.1Patch availableCNA
  • MapServer VendorOSGeo Affected 4.2 to before 8.6.1 Fixed in 8.6.1 Patch available CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:osgeo:mapserver:*:*:*:*:*:*:*:*4.2.0 to before 8.6.1VulnerableOSGeo
  • cpe:2.3:a:osgeo:mapserver:*:*:*:*:*:*:*:* Versions 4.2.0 to before 8.6.1 Vulnerable ·OSGeo

Remediation

  • Fix · CNA MapServer (MapServer) Fixed in 8.6.1

Vendor assessments

Red Hat

Red Hat's page for this CVE →

Not affected: 1 product
  • Red Hat

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-33721

References

Exploit 1

Other 1

  • TI-2025-36983 MapServer - WFS XML Filter Query SQL injection CVSS 4.0HIGH 8.9
  • TI-2026-30409 MapServer: Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS) in OpenLayers viewer CVSS 3.1MEDIUM 6.1
  • TI-2009-00797 Stack-based buffer overflow in mapserv.c in mapserv in MapServer 4.x before 4.10.4 and… CVSS 2.0HIGH 10.0
  • TI-2009-02173 Multiple heap-based buffer underflows in the readPostBody function in cgiutil.c in… CVSS 2.0HIGH 10.0
  • TI-2009-00799 Directory traversal vulnerability in mapserv.c in mapserv in MapServer 4.x before 4.10.4… CVSS 2.0HIGH 10.0
  • TI-2009-00798 Heap-based buffer underflow in the readPostBody function in cgiutil.c in mapserv in… CVSS 2.0HIGH 10.0
See all 21 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences