CVE-2025-59839 is a high-severity cross-site scripting (XSS) vulnerability in starcitizenwiki/embedvideo (composer), affecting versions <= 4.0.0. No fixed version is listed yet.
Summary The EmbedVideo extension allows adding arbitrary attributes to an HTML element, allowing for stored XSS through wikitext. Details The attributes of an iframe are populated with the value of an unreserved data attribute (data-iframeconfig) that can be set via wikitext: https://github.com/StarCitizenWiki/mediawiki-extensions-EmbedVideo/blob/440fb331a84b2050f4cc084c1d31d58a1d1c202d/resources/ext.embedVideo.videolink.js#L5-L20 Similar code is also present here: https://github.com/StarCitizenWiki/mediawiki-extensions-EmbedVideo/blob/440fb331a84b2050f4cc084c1d31d58a1d1c202d/resources/modules/iframe.js#L139-L155 It is possible to execute JS through attributes like onload or onmouseenter. PoC Create a page with the following contents: Click on the "Click me!" text Click on the "Load video" button below <img width="855" height="404" alt="image" src="https://github.com/user-attachments/assets/afb3839a-012c-4e90-a208-a6137b704ccd" /> Impact Arbitrary HTML can be inserted into the DOM by any user, allowing for JavaScript to be executed.
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-2025-59839 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.
No fixed version is listed yet, so configuration controls and monitoring matter more in the interim.
composer
starcitizenwiki/embedvideo (<= 4.0.0)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-2025-59839 is reachable in your applications. Explore open-source security for your team.
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No fixed version is listed for CVE-2025-59839 yet.
In the interim: Validate and encode untrusted input before rendering it as HTML. Applying a Content Security Policy reduces the impact if encoding is bypassed.
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
CVE-2025-59839 is a high-severity cross-site scripting (XSS) vulnerability in starcitizenwiki/embedvideo (composer), affecting versions <= 4.0.0. No fixed version is listed yet. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
CVE-2025-59839 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.
starcitizenwiki/embedvideo (composer) versions <= 4.0.0 is affected.
No fixed version is listed for CVE-2025-59839 yet. Monitor the advisory for updates and apply mitigations in the interim.
Whether CVE-2025-59839 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.
No fixed version is listed yet. In the interim: Validate and encode untrusted input before rendering it as HTML. Applying a Content Security Policy reduces the impact if encoding is bypassed.