Medium
Security advisory
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).
- Products
- Not specified
- Affected versions
- Not specified
- Fixed versions
- Not specified
- CVEs
- CVE-2021-26271
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 1 Nov 2026, 08:46 UTC · Revision 1
Source evidence
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).
osv:CVE-2021-26271
Complete source record
{
"id": "0a6d639fcf8314f571e03b8eb6e1f6c52eb07eafdf8af814bb7c4a0fe1a3385d",
"url": "https://osv.dev/vulnerability/CVE-2021-26271",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "CVE-2021-26271",
"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).",
"evidence": "osv:CVE-2021-26271",
"products": [],
"severity": "medium",
"structured": {
"id": "CVE-2021-26271",
"aliases": [
"CVE-2021-26271",
"GHSA-jv4c-7jqq-m34x"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H"
}
],
"affected": [
{
"ranges": [
{
"repo": "https://github.com/ckeditor/ckeditor4",
"type": "GIT",
"events": [
{
"introduced": "769d96134bcf29f5d3d870e25797ce9b9dc8289e"
},
{
"fixed": "17a1555f7fbb0e83f737c9efe27650dca8dff36f"
}
],
"database_specific": {
"extracted_events": [
{
"cpe": "cpe:2.3:a:ckeditor:ckeditor:*:*:*:*:*:*:*:*",
"range": [
{
"introduced": "4.0"
},
{
"fixed": "4.16"
}
],
"source": "CPE_RANGE"
}
]
}
}
],
"versions": [
"4.15.0",
"4.14.0",
"4.13.0",
"4.12.0",
"4.10.0",
"4.8.0",
"4.7.0",
"4.6.0",
"4.5.0",
"4.5.0-beta",
"4.4.1",
"4.4.0",
"4.2.3",
"4.2.2",
"4.2.1",
"4.2.0",
"4.2",
"4.1.0",
"4.1",
"4.1rc",
"4.0.1",
"4.0.0",
"4.0"
],
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-26271.json"
}
},
{
"ranges": [
{
"repo": "https://github.com/ckeditor/ckeditor4-releases",
"type": "GIT",
"events": [
{
"introduced": "870a561110a23435d78eda377400dca7f64d3bd3"
},
{
"fixed": "a393696ad5523e9f5ffab76e9b653240c49c770b"
}
],
"database_specific": {
"extracted_events": [
{
"cpe": "cpe:2.3:a:ckeditor:ckeditor:*:*:*:*:*:*:*:*",
"range": [
{
"introduced": "4.0"
},
{
"fixed": "4.16"
}
],
"source": "CPE_RANGE"
}
]
}
}
],
"versions": [
"standard/4.15.1",
"standard/4.15.0",
"standard/4.14.1",
"standard/4.14.0",
"standard/4.13.1",
"standard/4.13.0",
"standard/4.12.1",
"standard/4.12.0",
"standard/4.11.4",
"standard/4.11.3",
"standard/4.11.2",
"standard/4.11.1",
"standard/4.11.0",
"standard/4.10.1",
"standard/4.10.0",
"standard/4.9.2",
"standard/4.9.1",
"standard/4.9.0",
"standard/4.8.0",
"standard/4.7.3",
"standard/4.7.2",
"standard/4.7.1",
"standard/4.7.0",
"standard/4.6.2",
"standard/4.6.1",
"standard/4.6.0",
"standard/4.5.11",
"standard/4.5.10",
"standard/4.5.9",
"standard/4.5.8",
"standard/4.5.7",
"standard/4.5.6",
"standard/4.5.5",
"standard/4.5.4",
"standard/4.5.3",
"standard/4.5.2",
"standard/4.5.1",
"standard/4.5.0",
"standard/4.4.8",
"standard/4.4.7",
"standard/4.4.6",
"standard/4.4.5",
"standard/4.4.4",
"standard/4.4.3",
"standard/4.4.2",
"standard/4.4.1",
"standard/4.4.0",
"standard/4.3.5",
"standard/4.3.4",
"standard/4.3.3",
"4.3.2/standard",
"4.3.1/standard",
"4.3.0/standard",
"4.2.3/standard",
"4.2.2/standard",
"4.2.1/standard",
"4.2/standard",
"4.1.3/standard",
"4.1.2/standard",
"4.1.1/standard",
"4.1/standard",
"4.1rc/standard",
"4.0.1/standard",
"4.0/standard"
],
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-26271.json"
}
}
],
"modified": "2026-10-24T10:50:07.405547400Z",
"provider": "osv",
"references": [
"https://ckeditor.com/blog/CKEditor-4.16-with-improved-image-pasting-High-Contrast-support-and-a-new-color-API/#security-comes-first",
"https://github.com/ckeditor/ckeditor4/blob/major/CHANGES.md#ckeditor-416",
"https://www.oracle.com//security-alerts/cpujul2021.html",
"https://www.oracle.com/security-alerts/cpuoct2021.html"
],
"provider_metadata": {
"unresolved_ranges": [
{
"cpes": [
"cpe:2.3:a:oracle:application_express:*:*:*:*:*:*:*:*"
],
"vendor_product": "oracle:application_express",
"extracted_events": [
{
"range": [
{
"fixed": "21.1.0"
}
],
"source": "CPE_RANGE"
}
]
},
{
"cpes": [
"cpe:2.3:a:oracle:financial_services_analytical_applications_infrastructure:*:*:*:*:*:*:*:*"
],
"vendor_product": "oracle:financial_services_analytical_applications_infrastructure",
"extracted_events": [
{
"range": [
{
"introduced": "8.0.6"
},
{
"last_affected": "8.0.9"
}
],
"source": "CPE_RANGE"
}
]
},
{
"cpes": [
"cpe:2.3:a:oracle:jd_edwards_enterpriseone_tools:*:*:*:*:*:*:*:*"
],
"vendor_product": "oracle:jd_edwards_enterpriseone_tools",
"extracted_events": [
{
"range": [
{
"fixed": "9.2.6.0"
}
],
"source": "CPE_RANGE"
}
]
},
{
"cpes": [
"cpe:2.3:a:oracle:siebel_ui_framework:*:*:*:*:*:*:*:*"
],
"vendor_product": "oracle:siebel_ui_framework",
"extracted_events": [
{
"range": [
{
"fixed": "21.9"
}
],
"source": "CPE_RANGE"
}
]
},
{
"cpes": [
"cpe:2.3:a:oracle:agile_product_lifecycle_management:9.3.5:*:*:*:*:*:*:*",
"cpe:2.3:a:oracle:agile_product_lifecycle_management:9.3.6:*:*:*:*:*:*:*"
],
"vendor_product": "oracle:agile_product_lifecycle_management",
"extracted_events": [
{
"range": [
{
"introduced": "9.3.5"
},
{
"last_affected": "9.3.5"
},
{
"introduced": "9.3.6"
},
{
"last_affected": "9.3.6"
}
],
"source": "CPE_STRING"
}
]
},
{
"cpes": [
"cpe:2.3:a:oracle:financial_services_analytical_applications_infrastructure:8.1.0:*:*:*:*:*:*:*",
"cpe:2.3:a:oracle:financial_services_analytical_applications_infrastructure:8.1.1:*:*:*:*:*:*:*"
],
"vendor_product": "oracle:financial_services_analytical_applications_infrastructure",
"extracted_events": [
{
"range": [
{
"introduced": "8.1.0"
},
{
"last_affected": "8.1.0"
},
{
"introduced": "8.1.1"
},
{
"last_affected": "8.1.1"
}
],
"source": "CPE_STRING"
}
]
},
{
"cpes": [
"cpe:2.3:a:oracle:webcenter_sites:12.2.1.3.0:*:*:*:*:*:*:*",
"cpe:2.3:a:oracle:webcenter_sites:12.2.1.4.0:*:*:*:*:*:*:*"
],
"vendor_product": "oracle:webcenter_sites",
"extracted_events": [
{
"range": [
{
"introduced": "12.2.1.3.0"
},
{
"last_affected": "12.2.1.3.0"
},
{
"introduced": "12.2.1.4.0"
},
{
"last_affected": "12.2.1.4.0"
}
],
"source": "CPE_STRING"
}
]
}
]
}
},
"related_cves": [
{
"value": "CVE-2021-26271",
"evidence": "/id"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 441975,
"published_at": "2021-01-26T21:15:12.86+00:00"
}