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VulnerabilityPublished

CVE-2026-52854: mediawiki/maps has stored XSS through the overlays parameter in the display_map parser function

Affects mediawiki/mapsSource GCVE Database

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Authoritative record:CVE-2026-52854· High 8.6

Not known to be exploited · CVSS 8.6 High : upgrade to 12.1.3 soon.

Data as of 29 Oct 2026, 19:04 UTC

CVSS 3.1 base score
8.6High
How severe the flaw is on the 0–10 CVSS scale.
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:L

Exploitation evidence

t = 0 is the CVE’s publication on cve.org

  1. Disclosed: evidence found.

    CVE published 18 Aug 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: evidence found.

    CISA SSVC: proof of concept public

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

Timeline

  1. CVE ID reserved

    by GitHub, Inc.

    , 71 days before disclosure

  2. CVE published

    on cve.org

    , t = 0

  3. 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

ProductAffectedFixed in
Packagistmediawiki/mapsAffected
  • <12.1.3
Fixed in
  • 12.1.3

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.

References

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