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Response snapshot Oct 27, 2026, 21:36 UTC

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VulnerabilityCVE-2026-116688

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

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.

At a glance

Exploited
Not known
Severity
8.1 High (CVSS 3.1)
Chance of exploitation
Not estimated
Sources
2 independent sources

What to do

GitHub lists first patched versions: ckeditor5: 47.7.4; @ckeditor/ckeditor5-engine: 47.7.4; ckeditor5: 48.5.1; @ckeditor/ckeditor5-engine: 48.5.1. Confirm the affected range and upgrade guidance in the exact advisory.

Read GitHub-reviewed advisory GHSA-rh54-vffm-5fvp (opens a new tab)

What happened

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

Continue reading

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.

Affected package ranges reported by GitHub: ckeditor5: >= 45.0.0, < 47.7.4 @ckeditor/ckeditor5-engine: >= 45.0.0, < 47.7.4 ckeditor5: >= 48.0.0, < 48.5.1 @ckeditor/ckeditor5-engine: >= 48.0.0, < 48.5.1

Scores and how they were measured

CVSS base severity

8.1

Version 3.1As of

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

Measurement source (opens a new tab)

How bad it is if exploited. Not a prediction of exploitation or proof you are exposed.

EPSS probability

Not available

A model's estimate of exploitation in the next 30 days, not certainty or your own risk.

Related technology

Sources

  1. Primary source

    GitHub-reviewed advisory GHSA-rh54-vffm-5fvp (opens a new tab)

    The public advisory supplies the description, affected package/version ranges, and any listed CVSS metric. GitHub review is not local review.

    Published Checked

  2. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-rh54-vffm-5fvp, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  3. Primary source

    NVD CVE-2026-116688 (opens a new tab)

    NVD record: description, CVSS (the CNA score is preferred), affected products, and publication date. Not evidence of exploitation.

    Published Checked

  4. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  5. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  6. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

Cite this record

For factual claims, cite the primary sources above; cite KEVWire for its compilation, dates, and classifications.

APA

KEVWire. (2026, October 27). CKEditor: Cross-site scripting (XSS) in the engine package (CVE-2026-116688). https://kevwire.com/record/CVE-2026-116688

MLA

"CKEditor: Cross-site scripting (XSS) in the engine package (CVE-2026-116688)." KEVWire, 27 Oct. 2026, kevwire.com/record/CVE-2026-116688.

Chicago

KEVWire. "CKEditor: Cross-site scripting (XSS) in the engine package (CVE-2026-116688)." Last modified October 27, 2026. https://kevwire.com/record/CVE-2026-116688.

Evidence summary (plain text)

CKEditor: Cross-site scripting (XSS) in the engine package (Oct 27, 2026).
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.

The problem has been recognized and patched. The fix will be available in version 48.5.1 (and above) and 47.7.4 (LTS).
CVSS 8.1 (version 3.1; evidence as of Oct 27, 2026; https://github.com/advisories/GHSA-rh54-vffm-5fvp).
Sources:
GitHub-reviewed advisory GHSA-rh54-vffm-5fvp: https://github.com/advisories/GHSA-rh54-vffm-5fvp
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc
NVD CVE-2026-116688: https://nvd.nist.gov/vuln/detail/CVE-2026-116688
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-10-27T20:06:01.291Z&lastModEndDate=2026-10-27T21:35:56.840Z&resultsPerPage=500&startIndex=0
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-10-27T19:31:06.519Z&lastModEndDate=2026-10-27T21:05:56.923Z&resultsPerPage=500&startIndex=0
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-10-27T19:00:59.356Z&lastModEndDate=2026-10-27T20:30:57.738Z&resultsPerPage=500&startIndex=0
Record ID: CVE-2026-116688.
Record origin: Ingested record.
AI evidence: Not assessed.
Known exploitation: Not assessed.
Zero-day status: Not assessed. KEV membership alone does not establish zero-day status.
About this data

This record was ingested from a data source. Retrieved: Oct 27, 2026, 21:35 UTC. Ingestion is not an independent editorial investigation.

A CISA KEV listing documents known exploitation, not necessarily a zero-day; absence from the catalog does not prove a vulnerability has never been exploited.

Technology tags indicate possible relevance, not verified exposure. Confirm the affected product, version, and configuration against your own inventory; KEVWire does not scan your systems.

A personal reading checklist on this device, not verified remediation.

Record JSON

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Record details

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