CVE-2026-52854: mediawiki/maps has stored XSS through the overlays parameter in the display_map parser function
Affects mediawiki/mapsSource GCVE Database
Not known to be exploited · CVSS 8.6 High : upgrade to 12.1.3 soon.
Data as of 29 Oct 2026, 19:04 UTC
- EPSS
- 0.5% chance of exploitation in 30 days – higher than 47% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 12.1.3
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:LExploitation evidence
t = 0 is the CVE’s publication on cve.org
Disclosed: evidence found.
CVE published 18 Aug 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: evidence found.
CISA SSVC: proof of concept public
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
Timeline
CVE ID reserved
by GitHub, Inc.
, 71 days before disclosure
CVE published
on cve.org
, t = 0
CISA SSVC assessment
proof of concept public
, 21 hours after disclosure
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), CISA SSVC, the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.
What to do
Upgrade mediawiki/maps to 12.1.3.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| Packagistmediawiki/maps | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
Description
### Summary Stored XSS through wikitext can be performed by inserting malicious HTML into the `overlays` parameter of the `display_map` parser function when using the leaflet service. ### Details The maps extension doesn't escape overlay names before passing them to leaflet. Leaflet then inserts them as HTML: https://github.com/ProfessionalWiki/Maps/blob/ca5139fabd75f3c34f47ea3fd161306506b053bc/resources/lib/leaflet/leaflet.js#L5243 ### PoC Preview the following wikitext, using the default configuration options of the extension: ``` {{#display_map:0,0|service=leaflet|overlays=OpenTopoMap.<img src=x onerror="alert(1);">}} ``` ### Impact Stored XSS can be performed by any user with the `edit` permission.