CVE-2026-54355MapServer: Reflected XSS in OpenLayers HTML Output via `HTTP_X_FORWARDED_HOST`
- 5.3MediumCVSS base score
- 0.50%Exploitation in 30 daysEPSS · top 57% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- YesPublic exploitsa reference or SSVC says so
Description
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.
Public exploit
An exploit or proof of concept is public: anyone can try it against an unpatched system. A reference of the record is tagged as an exploit. CISA's SSVC rates its exploitation: a proof of concept is public.
Show the exploits1
References tagged exploit1 reference
- https://github.com/MapServer/MapServer/security/advisories/GHSA-xqj6-vjqr-33vv (opens in a new tab)x_refsource_CONFIRMexploit
Timeline
ID reserved
By GitHub_M
- 3 months later
· 3 months later
Published
- 7 days later
· 7 days later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_MCNA (assigner) | 4.0 | Medium5.3 | CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N |
| NVDNVD · Awaiting Analysis | 4.0 | Medium5.3 | CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X |
- EPSS (exploitation in 30 days)
- 0.50% · top 57% of all CVEs (14 Nov 2026)
- CISA SSVC
- Exploitation: poc · Automatable: no · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 5.3.
Affected products
References
References7
- https://github.com/MapServer/MapServer/security/advisories/GHSA-xqj6-vjqr-33vv (opens in a new tab)x_refsource_CONFIRMexploit
- https://github.com/MapServer/MapServer/pull/7517 (opens in a new tab)x_refsource_MISC
- https://github.com/MapServer/MapServer/pull/7518 (opens in a new tab)x_refsource_MISC
- https://github.com/MapServer/MapServer/commit/edc1033c7963fcffd160d85cf430f49aaf4a1374 (opens in a new tab)x_refsource_MISC
- https://github.com/MapServer/MapServer/commit/ff17ef190caaeaa9002ac3d1c7969ec5315c345e (opens in a new tab)x_refsource_MISC
- https://github.com/MapServer/MapServer/releases/tag/rel-8-6-4 (opens in a new tab)x_refsource_MISC
- https://mapserver.org/development/changelog/changelog-8-6.html#changelog-8-6 (opens in a new tab)x_refsource_MISC
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-82433 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-54355)Record last updated .