How severe is CVE-2024-21908?

CVE-2024-21908 has a CVSS score of 6.1/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2024-21908?

CVE-2024-21908 affects the following packages: tinymce (npm), TinyMCE (NuGet), tinymce/tinymce (Packagist). Ecosystems affected: npm, NuGet, Packagist.

How do I fix CVE-2024-21908?

Update tinymce to 5.9.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2024-21908 is resolved across your whole dependency graph.

How do I detect CVE-2024-21908 in my npm, NuGet, Packagist dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for tinymce. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate CVE-2024-21908 if there is no patch (or I can't update yet)?

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 does O3 Security protect against CVE-2024-21908?

O3 pinpoints whether CVE-2024-21908 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is CVE-2024-21908 actively exploited in the wild?

Yes. There are 2 known exploit references for CVE-2024-21908, including 2 in-the-wild exploitations observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2024-21908?

CVE-2024-21908 has an EPSS (Exploit Prediction Scoring System) score of 1.1%, placing it in the 60th 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.

When was CVE-2024-21908 published, and has it been updated?

CVE-2024-21908 was published on January 3, 2024 and was last updated on April 10, 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

CVE-2024-21908

MEDIUM

Cross-site scripting vulnerability in TinyMCE

Also known asGHSA-5h9g-x5rv-25wg

Published

Jan 3, 2024

Updated

Apr 10, 2026

Affected

3 pkgs

Patched

3 / 3

Exploits

2 known

EPSS Exploitation Probability

via FIRST.org ↗

1.1%probability of exploitation in next 30 days

Lower Risk60th percentile+0.55%

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.

Blast Radius

3 pkgs affected

Weekly download volume for affected packages — a proxy for how broadly this vulnerability is deployed.

tinymcenpm

1.1Mdownloads / week

Description

TinyMCE versions before 5.9.0 are affected by a stored cross-site scripting vulnerability. An unauthenticated and remote attacker could insert crafted HTML into the editor resulting in arbitrary JavaScript execution in another user's browser.

Affected Packages

3 total 3 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`tinymce`	all versions	5.9.0
.NETNuGet	`TinyMCE`	all versions	5.9.0
🐘Packagist	`tinymce/tinymce`	all versions	5.9.0

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

TinyMCE versions before 5.9.0 are affected by a stored cross-site scrip…

github.comNVDJan 2024

TinyMCE versions before 5.9.0 are affected by a stored cross-site scrip…

github.comNVDJan 2024

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for tinymce. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update tinymce to 5.9.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2024-21908 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 pinpoints whether CVE-2024-21908 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to CVE-2024-21908. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

O3 Security · Impact-Aware SCA

Is CVE-2024-21908 in your dependencies?

O3 detects CVE-2024-21908 across npm, NuGet, Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

Scan my dependencies How O3 SCA works