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MEDIUM severity

GHSA-jv4c-7jqq-m34x ckeditor4-dev

MEDIUM

GHSA-jv4c-7jqq-m34x is a medium-severity (CVSS 6.5) CWE-829 vulnerability in ckeditor4-dev. A fix is available for ckeditor4-dev — see the affected versions and patch details below.

CKEditor 4 ReDoS Vulnerability

Also known asCVE-2021-26271
Published
May 24, 2022
Updated
Sep 10, 2026
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Sep 20, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
2.0%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs80th percentile — riskier than 80% of all scored CVEsHighest risk

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

How urgent is this, really

GHSA-jv4c-7jqq-m34x plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.

Where this sits among everything scored

Of 377,333 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.

Real-World Exposure

1 pkg affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, a proxy for how much of the ecosystem is exposed.

ckeditor4-devnpm
36downloads / week

Description

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).

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
📦npmckeditor4-devall versions4.16npm install ckeditor4-dev@4.16

Detection & mitigation playbook

Open-source dependency
  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for ckeditor4-dev, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update ckeditor4-dev to 4.16 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-jv4c-7jqq-m34x is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

  4. How O3 protects you

    O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-jv4c-7jqq-m34x can be triaged on real exposure rather than presence alone.

Tailored to GHSA-jv4c-7jqq-m34x. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

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).
O3 Security · Impact-Aware SCA

Is GHSA-jv4c-7jqq-m34x in your dependencies?

O3 Security finds GHSA-jv4c-7jqq-m34x across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.

GHSA-jv4c-7jqq-m34x: ckeditor4-dev | O3 Security