Summary
TinyMCE Cross-Site Scripting (XSS) vulnerability in handling iframes
Workarounds
The HTTP Content-Security-Policy (CSP) frame-src or object-src can be configured to restrict or block the loading of unauthorized URLS. Refer to the TinyMCE Content Security Policy Guide.
References
Impact
A cross-site scripting (XSS) vulnerability was discovered in TinyMCE’s content insertion code. This allowed iframe elements containing malicious code to execute when inserted into the editor. These iframe elements are restricted in their permissions by same-origin browser protections, but could still trigger operations such as downloading of malicious assets.
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-2024-29203 has a CVSS score of 4.3 (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 (6.8.1); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
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. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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TinyMCE 6.8.1 introduced a new sandbox_iframes boolean option which adds the sandbox="" attribute to every iframe element by default when enabled. This will prevent cross-origin, and in special cases same-origin, XSS by embedded resources in iframe elements. From TinyMCE 7.0.0 onwards the default value of this option is true.
In TinyMCE 7.0.0 a new sandbox_iframes_exclusions option was also added, allowing a list of domains to be specified that should be excluded from having the sandbox="" attribute applied when the sandbox_iframes option is enabled. By default, this option is set to an array of domains that are provided in embed code by popular websites. To sandbox iframe elements from every domain, set this option to [].
Frequently Asked Questions
- What is CVE-2024-29203? CVE-2024-29203 is a medium-severity cross-site scripting (XSS) vulnerability in tinymce (npm), affecting versions < 6.8.1. It is fixed in 6.8.1. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
- How severe is CVE-2024-29203? CVE-2024-29203 has a CVSS score of 4.3 (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.
- Which packages are affected by CVE-2024-29203?
tinymce(npm) (versions < 6.8.1)TinyMCE(nuget) (versions < 6.8.1)tinymce/tinymce(composer) (versions < 6.8.1)
- Is there a fix for CVE-2024-29203? Yes. CVE-2024-29203 is fixed in 6.8.1. Upgrade to this version or later.
- Is CVE-2024-29203 exploitable, and should I be worried? Whether CVE-2024-29203 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
- What actually determines whether CVE-2024-29203 is exploitable, and how bad it is? 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.
- How do I fix CVE-2024-29203?
- Upgrade
tinymceto 6.8.1 or later - Upgrade
TinyMCEto 6.8.1 or later - Upgrade
tinymce/tinymceto 6.8.1 or later
- Upgrade