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NVD / CVE Program· CNA mitre

CVE-2021-26271: 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 in

Noroxi assessment

Priority: Monitor (action score 27/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 1.9% (FIRST EPSS); higher than 80.6% of all records.
  • Anyone who can reach it over the internet can trigger it. No account or password is required. A user must open a link or visit a page. No special conditions are required; it is repeatable.
  • Fixed version: ckeditor (Debian:12) 4.16.0+dfsg-1; ckeditor4-dev (npm) 4.16.

Low priority for now. Upgrade to ckeditor (Debian:12) 4.16.0+dfsg-1; ckeditor4-dev (npm) 4.16 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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).

MediumCVSS 6.5 · v3.1—No exploit Fix available
Published
Jan 26, 2021
Updated
Aug 25, 2026
EPSS
1.9% · 80th percentile

Report tools

JSON

Action score

27

Monitor

Low priority for now.

CVSS
26 / 40 · 6.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
1 / 30 · 1.9%

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

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When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
ckeditorckeditor
oracleagile product lifecycle management
oracleapplication express
oraclefinancial services analytical applications infrastructure
oraclejd edwards enterpriseone tools
oraclesiebel ui framework
oraclewebcenter sites

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • ckeditor ckeditor4.0 and later · before 4.16
  • oracle agile product lifecycle management9.3.5
  • oracle agile product lifecycle management9.3.6
  • oracle application expressbefore 21.1.0
  • oracle financial services analytical applications infrastructure8.0.6 and later · up to 8.0.9 inclusive
  • oracle financial services analytical applications infrastructure8.1.0
  • oracle financial services analytical applications infrastructure8.1.1
  • oracle jd edwards enterpriseone toolsbefore 9.2.6.0
  • oracle siebel ui frameworkbefore 21.9
  • oracle webcenter sites12.2.1.3.0
  • oracle webcenter sites12.2.1.4.0

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12ckeditorbefore 4.16.0+dfsg-14.16.0+dfsg-1
npmckeditor4-devbefore 4.164.16

Same product

ckeditor: all records

Other highest-scoring records for the same primary product.

  • CVE-2023-31541A unrestricted file upload vulnerability was discovered in the ‘Browse and upload images’ feature of the CKEditor v1.2.3 plugin for Redmine,
    39Monitor
  • CVE-2022-24729Regular expression Denial of Service in dialog plugin
    31Monitor
  • CVE-2011-4972hook_file_download in the CKEditor module 7.x-1.4 for Drupal does not properly restrict access to private files, which allows remote attacke
    31Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2020-9440Mar 10, 2020 · A cross-site scripting (XSS) vulnerability in the WSC plugin through 5.5.7.5 for CKEditor 4 allows remote attackers to run arbitrary web scr
    24Monitor
  • ← EarlierCVE-2020-27193Nov 12, 2020 · A cross-site scripting (XSS) vulnerability in the Color Dialog plugin for CKEditor 4.15.0 allows remote attackers to run arbitrary web scrip
    25Monitor
  • Later →CVE-2021-26272Jan 26, 2021 · 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
    27Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
debian:ckeditor4.16.0+dfsg-1 · Debian:12Package registry (OSV)
npm:ckeditor4-dev4.16Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • A user must open a link or visit a page.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
Required
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-829 · Inclusion of Functionality from Untrusted Control Sphere

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (3 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records