{"id":"CVE-2021-26271","title":"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).","summary":"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).","severity":"medium","cvss":6.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H","cwe":["CWE-829"],"vendor":"ckeditor","product":"ckeditor","affected":["ckeditor >= 4.0, < 4.16","agile_product_lifecycle_management = 9.3.5","agile_product_lifecycle_management = 9.3.6","application_express < 21.1.0","financial_services_analytical_applications_infrastructure >= 8.0.6, <= 8.0.9","financial_services_analytical_applications_infrastructure = 8.1.0","financial_services_analytical_applications_infrastructure = 8.1.1","jd_edwards_enterpriseone_tools < 9.2.6.0","siebel_ui_framework < 21.9","webcenter_sites = 12.2.1.3.0","webcenter_sites = 12.2.1.4.0"],"patched":["ckeditor 4.16","application_express 21.1.0","jd_edwards_enterpriseone_tools 9.2.6.0","siebel_ui_framework 21.9"],"published":"2021-01-26","updated":"2026-08-25","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2021-26271","references":[{"url":"https://ckeditor.com/blog/CKEditor-4.16-with-improved-image-pasting-High-Contrast-support-and-a-new-color-API/#security-comes-first","label":"cve@mitre.org"},{"url":"https://github.com/ckeditor/ckeditor4/blob/major/CHANGES.md#ckeditor-416","label":"cve@mitre.org"},{"url":"https://www.oracle.com//security-alerts/cpujul2021.html","label":"cve@mitre.org"},{"url":"https://www.oracle.com/security-alerts/cpuoct2021.html","label":"cve@mitre.org"},{"url":"https://ckeditor.com/blog/CKEditor-4.16-with-improved-image-pasting-High-Contrast-support-and-a-new-color-API/#security-comes-first","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://github.com/ckeditor/ckeditor4/blob/major/CHANGES.md#ckeditor-416","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://www.oracle.com//security-alerts/cpujul2021.html","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://www.oracle.com/security-alerts/cpuoct2021.html","label":"af854a3a-2127-422b-91ae-364da2661108"}],"tags":["nvd"],"epss":0.0197,"epssPercentile":0.79283,"ingestedAt":"2026-08-25T17:29:31.056Z","slug":"CVE-2021-26271","body":"## Overview\n\nIt 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).\n\n## Affected\n\n- `ckeditor >= 4.0, < 4.16`\n- `agile_product_lifecycle_management = 9.3.5`\n- `agile_product_lifecycle_management = 9.3.6`\n- `application_express < 21.1.0`\n- `financial_services_analytical_applications_infrastructure >= 8.0.6, <= 8.0.9`\n- `financial_services_analytical_applications_infrastructure = 8.1.0`\n- `financial_services_analytical_applications_infrastructure = 8.1.1`\n- `jd_edwards_enterpriseone_tools < 9.2.6.0`\n- `siebel_ui_framework < 21.9`\n- `webcenter_sites = 12.2.1.3.0`\n- `webcenter_sites = 12.2.1.4.0`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `ckeditor 4.16`\n- `application_express 21.1.0`\n- `jd_edwards_enterpriseone_tools 9.2.6.0`\n- `siebel_ui_framework 21.9`","depth":"sunlit","depthScore":36,"depthScoreParts":{"impact":35.8,"likelihood":0.4,"exploitation":0,"ransomware":0},"changes":[]}