high · 8.1 Patched

CKEditor: Cross-site scripting (XSS) in the engine package

CVE-2026-116688 · GHSA-rh54-vffm-5fvp · published 27 Oct 2026

How serious is it

  • Severity: high, CVSS score 8.1 out of 10.
  • No exploit prediction (EPSS) score yet.
  • Not on the CISA list of exploited vulnerabilities.
  • No public exploit in Exploit-DB.

Is your app affected by CVE-2026-116688?

Paste this prompt into Claude Code, Cursor or any AI coding tool: it runs a free Shippable scan of your project and fixes what it finds. Built with Lovable, Bolt or v0? Scan your live app. Or upload your package file.

Who is affected

  • ckeditor5 (npm) >= 45.0.0, < 47.7.4
  • @ckeditor/ckeditor5-engine (npm) >= 45.0.0, < 47.7.4
  • ckeditor5 (npm) >= 48.0.0, < 48.5.1
  • @ckeditor/ckeditor5-engine (npm) >= 48.0.0, < 48.5.1

How to check

  1. Run npm ls ckeditor5 in your project to see the installed version, including copies pulled in by other packages.
  2. Run npm ls @ckeditor/ckeditor5-engine in your project to see the installed version, including copies pulled in by other packages.
  3. Or paste your lockfile into the checker: it lists every package with a known vulnerability, this one included.
  4. Or run npx shippable-dev scan localhost:3000 in your project folder. It reads your lockfile and flags this vulnerability along with every other known one.

How to fix

Copies a prompt for Claude Code, Cursor or Codex: it checks your lockfiles for this and upgrades it.
  1. On >= 45.0.0, < 47.7.4: Upgrade ckeditor5 to 47.7.4 or later, commit the lockfile and redeploy.
  2. On >= 45.0.0, < 47.7.4: Upgrade @ckeditor/ckeditor5-engine to 47.7.4 or later, commit the lockfile and redeploy.
  3. On >= 48.0.0, < 48.5.1: Upgrade ckeditor5 to 48.5.1 or later, commit the lockfile and redeploy.
  4. On >= 48.0.0, < 48.5.1: Upgrade @ckeditor/ckeditor5-engine to 48.5.1 or later, commit the lockfile and redeploy.
  5. If a vulnerable version was live, check your logs and rotate the secrets that server could read.

The advisory

### Impact A Cross-Site Scripting (XSS) vulnerability has been discovered in the CKEditor 5 engine. This vulnerability is caused by a prototype pollution issue in the `es-toolkit` library used in the CKEditor 5 codebase. This vulnerability could lead to unauthorized JavaScript code execution when the editor processes incoming `style` attribute values. The underlying issue has been patched by the library maintainers, and the fix has been incorporated into CKEditor 5. ### Patches The problem has been recognized and patched. The fix will be available in version `48.5.1` (and above) and `47.7.4` (LTS). ### For more information Email us at [security@cksource.com](mailto:security@cksource.com) if you have any questions or comments about this advisory.

Check your whole app

Dependencies are only half of it. Free and read-only: before you push, run npx shippable-dev scan localhost:3000 in your project folder, no account needed. For your live app, you prove it's yours with a one-line tag first.

References

Merged from GitHub Advisory Database, OSV. Last updated 28 Oct 2026. All vulnerabilities · RSS · JSON

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