Cross-site Scripting (XSS) Affecting mapserver package, versions <8.6.4-1
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-DEBIANUNSTABLE-MAPSERVER-20029924
- published22 Sept 2026
- disclosed17 Sept 2026
Introduced: 17 Sep 2026
CVE-2026-54355 (opens in a new tab)How to fix?
Upgrade Debian:unstable mapserver to version 8.6.4-1 or higher.
NVD Description
Note: Versions mentioned in the description apply only to the upstream mapserver package and not the mapserver package as distributed by Debian.
See How to fix? for Debian:unstable relevant fixed versions and status.
MapServer is a system for developing web-based GIS applications. From 6.0 until 8.6.4, MapServer's OpenLayers HTML output for SERVICE=WMS&REQUEST=GetMap&FORMAT=application/openlayers reflects an attacker-controlled X-Forwarded-Host value received as HTTP_X_FORWARDED_HOST through msBuildOnlineResource(), processLine(), and the [mapserv_onlineresource] substitution in src/maputil.c and src/maptemplate.c without escaping it for a single-quoted JavaScript string. When the deployment trusts the forwarded header and does not configure a fixed ows_onlineresource or MS_ONLINERESOURCE value, embedded single quotes can escape the generated URL string. An unauthenticated attacker can craft a URL that executes arbitrary JavaScript in the MapServer site origin when opened by a victim, enabling access to sessions or tokens, same-origin data and requests, and actions as the victim. This issue is fixed in version 8.6.4.
References
- https://security-tracker.debian.org/tracker/CVE-2026-54355
- https://github.com/MapServer/MapServer/commit/edc1033c7963fcffd160d85cf430f49aaf4a1374
- https://github.com/MapServer/MapServer/commit/ff17ef190caaeaa9002ac3d1c7969ec5315c345e
- https://github.com/MapServer/MapServer/pull/7517
- https://github.com/MapServer/MapServer/pull/7518
- https://github.com/MapServer/MapServer/releases/tag/rel-8-6-4
- https://mapserver.org/development/changelog/changelog-8-6.html#changelog-8-6
- https://github.com/MapServer/MapServer/security/advisories/GHSA-xqj6-vjqr-33vv