CVE-2026-52854 is a high-severity cross-site scripting (XSS) vulnerability in mediawiki/maps (composer), affecting versions < 12.1.3. It is fixed in 12.1.3.
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: Impact Stored XSS can be performed by any user with the edit permission.
Untrusted input is rendered as active markup in a victim's browser, which can run script in their session. Typical impact: session or credential theft, and actions taken as the user.
CVE-2026-52854 has a CVSS score of 8.6 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment.
A fixed version is available (12.1.3). Upgrading removes the vulnerable code path.
composer
mediawiki/maps (< 12.1.3)mediawiki/maps → 12.1.3 (composer)Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter instead of chasing every advisory.
Kodem's runtime-powered SCA identifies whether CVE-2026-52854 is reachable in your applications. Explore open-source security for your team.
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Already deployed Kodem? See CVE-2026-52854 in your environment →Upgrade mediawiki/maps to 12.1.3 or later to resolve this vulnerability.
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
CVE-2026-52854 is a high-severity cross-site scripting (XSS) vulnerability in mediawiki/maps (composer), affecting versions < 12.1.3. It is fixed in 12.1.3. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
CVE-2026-52854 has a CVSS score of 8.6 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
mediawiki/maps (composer) versions < 12.1.3 is affected.
Yes. CVE-2026-52854 is fixed in 12.1.3. Upgrade to this version or later.
Whether CVE-2026-52854 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
Upgrade mediawiki/maps to 12.1.3 or later.