CVE-2026-42030

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.

CVSS v3.1 Score

6.1

MEDIUM

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

EPSS — Exploit Prediction

0.0002

Probability of exploitation

0.04%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-80 CWE-80

Affected Products

Vendor	Product	Versions
osgeo	mapserver	6.0.0 — 8.6.2

References

Advisories & Patches

https://github.com/MapServer/MapServer/security/advisories/GHSA-4g9f-ph64-hg2x https://github.com/MapServer/MapServer/security/advisories/GHSA-4g9f-ph64-hg2x

Exploits

https://github.com/MapServer/MapServer/security/advisories/GHSA-4g9f-ph64-hg2x https://github.com/MapServer/MapServer/security/advisories/GHSA-4g9f-ph64-hg2x

Other References

https://github.com/MapServer/MapServer/releases/tag/rel-8-6-2

Frequently Asked Questions

What is CVE-2026-42030? +

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. It has a CVSS v3.1 base score of 6.1 (MEDIUM).

How severe is CVE-2026-42030? +

CVE-2026-42030 has a CVSS v3.1 score of 6.1 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0002, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-42030? +

CVE-2026-42030 affects products from osgeo, specifically: mapserver. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-42030? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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