What’s Vulnerable › Vulnerabilities

CVE-2026-42030: MapServer: Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS) in OpenLayers viewer

• Severity: medium (CVSS 6.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-05-08 · updated 2026-06-17
• Weakness: CWE-80

Description

MapServer is a system for developing web-based GIS applications. From version 6.0 to before version 8.6.2, a reflected XSS vulnerability in MapServer's WMS server allows an unauthenticated attacker to inject arbitrary HTML/JavaScript into the browser of any user who opens a crafted WMS URL. The vulnerability is triggered via FORMAT=application/openlayers combined with an unsanitized SRS parameter in WMS 1.3.0 requests. This issue has been patched in version 8.6.2.

Affected products

• MapServer: from 6.0.0 before 8.6.2 — fixed in 8.6.2

How to fix

Upgrade to a fixed version: MapServer 8.6.2. Check the vendor advisory for mitigations.

References

• https://github.com/MapServer/MapServer/releases/tag/rel-8-6-2
• https://github.com/MapServer/MapServer/security/advisories/GHSA-4g9f-ph64-hg2x
• https://github.com/MapServer/MapServer/security/advisories/GHSA-4g9f-ph64-hg2x

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