CVE-2026-28343Network attack vector

Script execution via unsafe iframe attribute rendering

Published Mar 5, 2026 · Updated Mar 5, 2026

Cross-site scripting in CKEditor 5 before 47.6.0 allows remote authenticated users to execute JavaScript through crafted iframe markup. The editing pipeline rendered iframe srcdoc content and accepted javascript: or whitespace-obfuscated data: URLs without sanitizing those attributes. Exploitation requires General HTML Support to permit unsafe markup and grants script access to the surrounding page context without interrupting service.

CVSS severity6.4
Medium
EPSS probability0.27%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cross-site scripting in CKEditor 5 before 47.6.0 allows remote authenticated users to execute JavaScript through crafted iframe markup. The editing pipeline rendered iframe srcdoc content and accepted javascript: or whitespace-obfuscated data: URLs without sanitizing those attributes. Exploitation requires General HTML Support to permit unsafe markup and grants script access to the surrounding page context without interrupting service.

The record

CVE
CVE-2026-28343
Published
Mar 5, 2026
Updated
Mar 5, 2026
Vendor
CKSource
Product
CKEditor 5
Classifications
CWE-79, T1059.007
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 5, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 5, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 47.6.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

CKSource · CKEditor 5version=< 47.6.0

Published CVSS scores

6.4GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N
6.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1059.007JavaScript/JScript

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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