CVE-2024-29203 is a medium-severity (CVSS 4.3) Cross-site Scripting (XSS) vulnerability in tinymce. A fix is available for tinymce — see the affected versions and patch details below.
TinyMCE Cross-Site Scripting (XSS) vulnerability in handling iframes
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2024-29203.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2024-29203 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 378,567 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
tinymcenpmDescription
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.
Fix
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 [].
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
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | tinymce | all versions | 6.8.1npm install tinymce@6.8.1 |
| .NETNuGet | TinyMCE | all versions | 6.8.1dotnet add package TinyMCE --version 6.8.1 |
| 🐘Packagist | tinymce/tinymce | all versions | 6.8.1composer require tinymce/tinymce:^6.8.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for tinymce, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update tinymce to 6.8.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2024-29203 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2024-29203 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2024-29203. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2024-29203 in your dependencies?
O3 Security finds CVE-2024-29203 across npm, NuGet, Packagist dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.