GHSA-v626-r774-j7f8 — tinymce
MEDIUMGHSA-v626-r774-j7f8 is a medium-severity (CVSS 6.1) Cross-site Scripting (XSS) vulnerability in tinymce. A fix is available for tinymce — see the affected versions and patch details below.
TinyMCE vulnerable to mutation Cross-site Scripting via special characters in unescaped text nodes
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 GHSA-v626-r774-j7f8.
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
GHSA-v626-r774-j7f8 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 377,238 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 mutation cross-site scripting (mXSS) vulnerability was discovered in TinyMCE’s core undo/redo functionality and other APIs and plugins. Text nodes within specific parents are not escaped upon serialization according to the HTML standard. If such text nodes contain a special character reserved as an internal marker, they can be combined with other HTML patterns to form malicious snippets. These snippets pass the initial sanitisation layer when the content is parsed into the editor body, but can trigger XSS when the special internal marker is removed from the content and re-parsed. Such mutations occur when serialised HTML content is processed before being stored in the undo stack, or when the following APIs and plugins are used:
Patches
This vulnerability has been patched in TinyMCE 6.7.3 by:
- ensuring that any unescaped text nodes which contain the special internal marker are emptied before removing the marker from the rest of the HTML, and
- removing the special internal marker from content strings passed to
Editor.setContent,Editor.insertContent, andEditor.resetContentAPIs to prevent them from being loaded into the editor as user-provided content.
Fix
To avoid this vulnerability:
- Upgrade to TinyMCE 6.7.3 or higher for TinyMCE 6.x.
- Upgrade to TinyMCE 5.10.9 or higher for TinyMCE 5.x.
Acknowledgements
Tiny Technologies would like to thank Masato Kinugawa of Cure53 for discovering this vulnerability.
References
For more information
Email us at [email protected] Open an issue in the TinyMCE repo
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | tinymce | all versions | 5.10.9npm install tinymce@5.10.9 |
| 📦npm | tinymce | ≥ 6.0.0&&< 6.7.3 | 6.7.3npm install tinymce@6.7.3 |
| .NETNuGet | TinyMCE | all versions | 5.10.9dotnet add package TinyMCE --version 5.10.9 |
| .NETNuGet | TinyMCE | ≥ 6.0.0&&< 6.7.3 | 6.7.3dotnet add package TinyMCE --version 6.7.3 |
| 🐘Packagist | tinymce/tinymce | all versions | 5.10.9composer require tinymce/tinymce:^5.10.9 |
| 🐘Packagist | tinymce/tinymce | ≥ 6.0.0&&< 6.7.3 | 6.7.3composer require tinymce/tinymce:^6.7.3 |
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 5.10.9 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-v626-r774-j7f8 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 GHSA-v626-r774-j7f8 can be triaged on real exposure rather than presence alone.
Tailored to GHSA-v626-r774-j7f8. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-v626-r774-j7f8 in your dependencies?
O3 Security finds GHSA-v626-r774-j7f8 across npm, NuGet, Packagist dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.