CVE-2026-28343: CKEditor 5 has Cross-site Scripting (XSS) in the HTML Support package

March 4, 2026 (updated March 19, 2026)

A Cross-Site Scripting (XSS) vulnerability has been discovered in the General HTML Support feature. This vulnerability could be triggered by inserting specially crafted markup, leading to unauthorized JavaScript code execution, if the editor instance used an unsafe General HTML Support configuration.

This vulnerability affects only installations where the editor configuration meets the following criteria:

References

github.com/advisories/GHSA-jrqm-vmqc-gm93
github.com/ckeditor/ckeditor5
github.com/ckeditor/ckeditor5/releases/tag/v29.0.0
github.com/ckeditor/ckeditor5/releases/tag/v47.6.0
github.com/ckeditor/ckeditor5/security/advisories/GHSA-jrqm-vmqc-gm93
nvd.nist.gov/vuln/detail/CVE-2026-28343

Code Behaviors & Features

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