CVE-2024-21908 is a medium-severity cross-site scripting (XSS) vulnerability in tinymce (npm), affecting versions < 5.9.0. It is fixed in 5.9.0.
Impact A cross-site scripting (XSS) vulnerability was discovered in the schema validation logic of the core parser. The vulnerability allowed arbitrary JavaScript execution when inserting a specially crafted piece of content into the editor using the clipboard or editor APIs. This malicious content could then end up in content published outside the editor, if no server-side sanitization was performed. This impacts all users who are using TinyMCE 5.8.2 or lower. Patches This vulnerability has been patched in TinyMCE 5.9.0 by ensuring schema validation was still performed after unwrapping invalid elements. Workarounds To work around this vulnerability, either: Upgrade to TinyMCE 5.9.0 or higher Manually sanitize the content using the BeforeSetContent event (see below) Example: Manually sanitize content Acknowledgements Tiny Technologies would like to thank William Bowling for discovering this vulnerability. References https://www.tiny.cloud/docs/release-notes/release-notes59/#securityfixes For more information If you have any questions or comments about this advisory: Email us at [email protected] Open an issue in the TinyMCE repo
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-2024-21908 has a CVSS score of 6.1 (Medium). The vector is network-reachable, no privileges required, and user interaction required. 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 (5.9.0). Upgrading removes the vulnerable code path.
npm
tinymce (< 5.9.0)nuget
TinyMCE (< 5.9.0)composer
tinymce/tinymce (< 5.9.0)tinymce → 5.9.0 (npm)TinyMCE → 5.9.0 (nuget)tinymce/tinymce → 5.9.0 (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-2024-21908 is reachable in your applications. Explore open-source security for your team.
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Upgrade the following packages to resolve this vulnerability:
tinymce to 5.9.0 or laterTinyMCE to 5.9.0 or latertinymce/tinymce to 5.9.0 or laterKodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
CVE-2024-21908 is a medium-severity cross-site scripting (XSS) vulnerability in tinymce (npm), affecting versions < 5.9.0. It is fixed in 5.9.0. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
CVE-2024-21908 has a CVSS score of 6.1 (Medium). 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.
tinymce (npm) (versions < 5.9.0)TinyMCE (nuget) (versions < 5.9.0)tinymce/tinymce (composer) (versions < 5.9.0)Yes. CVE-2024-21908 is fixed in 5.9.0. Upgrade to this version or later.
Whether CVE-2024-21908 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.
tinymce to 5.9.0 or laterTinyMCE to 5.9.0 or latertinymce/tinymce to 5.9.0 or later