How severe is CVE-2024-29203?

CVE-2024-29203 has a CVSS score of 4.3/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2024-29203?

CVE-2024-29203 affects the following packages: tinymce (npm), TinyMCE (NuGet), tinymce/tinymce (Packagist). Ecosystems affected: npm, NuGet, Packagist.

How do I fix CVE-2024-29203?

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.

How do I detect CVE-2024-29203 in my npm, NuGet, Packagist dependencies?

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.

How do I mitigate CVE-2024-29203 if there is no patch (or I can't update yet)?

Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Is CVE-2024-29203 actively exploited in the wild?

No public exploit code has been indexed for CVE-2024-29203 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2024-29203?

CVE-2024-29203 has an EPSS (Exploit Prediction Scoring System) score of 0.7%, placing it in the 54th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2024-29203?

CVE-2024-29203 is classified as Cross-site Scripting (XSS) (CWE-79). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2024-29203 published, and has it been updated?

CVE-2024-29203 was published on March 26, 2024 and was last updated on October 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

📦

📦 npm.NET NuGet🐘 Packagist

Not in CISA KEV

MEDIUM severity

CVE-2024-29203 — tinymce

MEDIUMFix: tinymce/tinymce@bcdea2a

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

Also known asGHSA-438c-3975-5x3f

Published

Mar 26, 2024

Updated

Oct 28, 2026

Affected

3 pkgs

Patched

3 / 3

Exploits

None indexed

Exploitation data as of Nov 6, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

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

via FIRST.org ↗

0.7%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs54th percentile — riskier than 54% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

3 pkgs affected

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.

1Kother npm packages depend on this — each one inherits the vulnerability until it's patched upstream

tinymcenpm

1.5Mdownloads / week

Description

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

3 total 3 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`tinymce`	all versions	6.8.1`npm install tinymce@6.8.1`
.NETNuGet	`TinyMCE`	all versions	6.8.1`dotnet add package TinyMCE --version 6.8.1`
🐘Packagist	`tinymce/tinymce`	all versions	6.8.1`composer require tinymce/tinymce:^6.8.1`

Affected Products

1 product · 2 configurations

Application

tinymcetiny

≥ 6.8.2 && < 7.0.0

range

Detection & mitigation playbook

Open-source dependency

Detect
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
Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Frequently Asked Questions

### Impact A [cross-site scripting (XSS)](https://owasp.org/www-community/attacks/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 p