{"id":"CVE-2021-21391","details":"CKEditor 5 provides a WYSIWYG editing solution. This CVE affects the following npm packages: ckeditor5-engine, ckeditor5-font, ckeditor5-image, ckeditor5-list, ckeditor5-markdown-gfm, ckeditor5-media-embed, ckeditor5-paste-from-office, and ckeditor5-widget. Following an internal audit, a regular expression denial of service (ReDoS) vulnerability has been discovered in multiple CKEditor 5 packages. The vulnerability allowed to abuse particular regular expressions, which could cause a significant performance drop resulting in a browser tab freeze. It affects all users using the CKEditor 5 packages listed above at version \u003c= 26.0.0. The problem has been recognized and patched. The fix will be available in version 27.0.0.","aliases":["GHSA-3rh3-wfr4-76mj"],"modified":"2026-04-10T04:29:53.920823Z","published":"2021-04-29T01:15:07.883Z","related":["GHSA-3rh3-wfr4-76mj"],"references":[{"type":"WEB","url":"https://www.npmjs.com/package/%40ckeditor/ckeditor5-engine"},{"type":"WEB","url":"https://www.npmjs.com/package/%40ckeditor/ckeditor5-image"},{"type":"WEB","url":"https://www.npmjs.com/package/%40ckeditor/ckeditor5-widget"},{"type":"WEB","url":"https://www.npmjs.com/package/%40ckeditor/ckeditor5-font"},{"type":"WEB","url":"https://www.npmjs.com/package/%40ckeditor/ckeditor5-list"},{"type":"WEB","url":"https://www.npmjs.com/package/%40ckeditor/ckeditor5-markdown-gfm"},{"type":"WEB","url":"https://www.npmjs.com/package/%40ckeditor/ckeditor5-media-embed"},{"type":"WEB","url":"https://www.npmjs.com/package/%40ckeditor/ckeditor5-paste-from-office"},{"type":"ADVISORY","url":"https://github.com/ckeditor/ckeditor5/security/advisories/GHSA-3rh3-wfr4-76mj"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/ckeditor/ckeditor5","events":[{"introduced":"0"},{"fixed":"bf30aaa96be9b35cd6dca8563a7304fcd5092f63"},{"introduced":"0"},{"fixed":"bf30aaa96be9b35cd6dca8563a7304fcd5092f63"},{"introduced":"0"},{"fixed":"bf30aaa96be9b35cd6dca8563a7304fcd5092f63"},{"introduced":"0"},{"fixed":"bf30aaa96be9b35cd6dca8563a7304fcd5092f63"},{"introduced":"0"},{"fixed":"bf30aaa96be9b35cd6dca8563a7304fcd5092f63"},{"introduced":"0"},{"fixed":"bf30aaa96be9b35cd6dca8563a7304fcd5092f63"},{"introduced":"0"},{"fixed":"bf30aaa96be9b35cd6dca8563a7304fcd5092f63"},{"introduced":"0"},{"fixed":"bf30aaa96be9b35cd6dca8563a7304fcd5092f63"}],"database_specific":{"versions":[{"introduced":"0"},{"fixed":"27.0.0"},{"introduced":"0"},{"fixed":"27.0.0"},{"introduced":"0"},{"fixed":"27.0.0"},{"introduced":"0"},{"fixed":"27.0.0"},{"introduced":"0"},{"fixed":"27.0.0"},{"introduced":"0"},{"fixed":"27.0.0"},{"introduced":"0"},{"fixed":"27.0.0"},{"introduced":"0"},{"fixed":"27.0.0"}]}}],"versions":["10.1.0","v0.1.0","v0.10.0","v0.11.0","v0.2.0","v0.3.0","v0.4.0","v0.5.0","v0.6.0","v0.7.0","v0.9.0","v1.0.0-alpha.1","v1.0.0-alpha.2","v1.0.0-beta.1","v1.0.0-beta.2","v1.0.0-beta.4","v10.0.0","v10.1.0","v11.0.0","v11.1.0","v11.1.1","v11.2.0","v12.0.0","v12.1.0","v12.2.0","v12.3.0","v12.3.1","v15.0.0","v16.0.0","v17.0.0","v18.0.0","v19.0.0","v19.1.1"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-21391.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H"}]}