{"id":"CVE-2021-26271","aliases":["GHSA-jv4c-7jqq-m34x"],"url":"https://o3.security/vulnerability/CVE-2021-26271","summary":"CKEditor 4 ReDoS Vulnerability","details":"It was possible to execute a ReDoS-type attack inside CKEditor 4 before 4.16 by persuading a victim to paste crafted text into the Styles input of specific dialogs (in the Advanced Tab for Dialogs plugin).","published":"2021-01-26T21:15:12.860Z","modified":"2026-08-27T11:47:16.110307124Z","cvss":{"score":6.5,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H"},"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"npm","name":"ckeditor4-dev","fixedVersion":"4.16"}],"fix":null,"references":[{"type":"ADVISORY","url":"https://ckeditor.com/blog/CKEditor-4.16-with-improved-image-pasting-High-Contrast-support-and-a-new-color-API/#security-comes-first"},{"type":"ADVISORY","url":"https://github.com/ckeditor/ckeditor4/blob/major/CHANGES.md#ckeditor-416"},{"type":"FIX","url":"https://www.oracle.com//security-alerts/cpujul2021.html"},{"type":"FIX","url":"https://www.oracle.com/security-alerts/cpuoct2021.html"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-27T11:47:16.110307124Z"}}