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Fencer Vulns
medium 6.5

CVE-2021-26272 json

Inclusion of Functionality from Untrusted Control Sphere in CKEditor 4

published 2021-01-26 5 y ago modified 2026-08-25 2 mo ago also GHSA-wpvm-wqr4-p7cw , EUVD-2021-2267

cvss
6.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
2.4%
EPSS 2.4% chance of exploitation in 30 days, percentile 83%
public exploits
0
none known

Summary

It was possible to execute a ReDoS-type attack inside CKEditor 4 before 4.16 by persuading a victim to paste crafted URL-like text into the editor, and then press Enter or Space (in the Autolink plugin).

Patch / fix

  • npm ckeditor4 4.16.0
  • ckeditor ckeditor 4.16
  • oracle application_express 21.1.0
  • oracle jd_edwards_enterpriseone_tools 9.2.6.0
  • ckeditor Debian 12 4.16.0+dfsg-1

debian advisories DEBIAN-CVE-2021-26272

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-26272 updated cvss 4.7

ckeditor: Regular expression denial of service via crafted URL-like text

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

2.35% chance of exploitation in the next 30 days, higher than 83% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:N/I:N/A:P
GitHub 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
npm ckeditor4
<4.16.0
4.16.0

Classification

Weakness
  • CWE-829 Inclusion of Functionality from Untrusted Control Sphere

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.