{"id":"CVE-2021-41165","aliases":["BIT-drupal-2021-41165","GHSA-7h26-63m7-qhf2"],"url":"https://o3.security/vulnerability/CVE-2021-41165","summary":"HTML comments vulnerability allowing to execute JavaScript code","details":"### Affected packages\nThe vulnerability has been discovered in the core HTML processing module and may affect all plugins used by CKEditor 4.\n\n### Impact\nA potential vulnerability has been discovered in CKEditor 4 HTML processing core module. The vulnerability allowed to inject malformed comments HTML bypassing content sanitization, which could result in executing JavaScript code. It affects all users using the CKEditor 4 at version < 4.17.0.\n\n### Patches\nThe problem has been recognized and patched. The fix will be available in version 4.17.0.\n\n### For more information\nEmail us at security@cksource.com if you have any questions or comments about this advisory.\n\n### Acknowledgements\nThe CKEditor 4 team would like to thank William Bowling ([wbowling](https://github.com/wbowling)) for recognizing and reporting this vulnerability.\n","published":"2021-11-17T20:15:10.273Z","modified":"2026-07-08T06:29:57.864560628Z","cvss":{"score":5.4,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N"},"epss":{"score":0.01573,"percentile":0.74217,"asOf":"2026-09-17"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"npm","name":"ckeditor4","fixedVersion":"4.17.0"},{"ecosystem":"Packagist","name":"ckeditor/ckeditor","fixedVersion":"4.17.0"}],"fix":null,"references":[{"type":"WEB","url":"https://www.oracle.com/security-alerts/cpujul2022.html"},{"type":"ADVISORY","url":"https://github.com/ckeditor/ckeditor4/blob/major/CHANGES.md#ckeditor-417"},{"type":"ADVISORY","url":"https://github.com/ckeditor/ckeditor4/security/advisories/GHSA-7h26-63m7-qhf2"},{"type":"ADVISORY","url":"https://www.drupal.org/sa-core-2021-011"},{"type":"FIX","url":"https://www.oracle.com/security-alerts/cpuapr2022.html"},{"type":"FIX","url":"https://www.oracle.com/security-alerts/cpujan2022.html"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2021-41165"},{"type":"PACKAGE","url":"https://github.com/ckeditor/ckeditor4"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-07-08T06:29:57.864560628Z"}}