CVE-2024-21911Network attack vector

Stored XSS via core parser URL sanitization

Published Jan 3, 2024 · Updated Jul 14, 2026

Stored cross-site scripting in TinyMCE before 5.6.0 allows remote attackers to execute JavaScript in another user's browser via crafted HTML. The core parser's URL sanitization accepts unsafe URL attributes on iframe, object, and embed elements inserted through the clipboard or APIs. The attack requires a victim to load the stored content in an application embedding the editor, exposing data and actions available to that browser session.

CVSS severity6.1
Medium
EPSS probability1.17%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored cross-site scripting in TinyMCE before 5.6.0 allows remote attackers to execute JavaScript in another user's browser via crafted HTML. The core parser's URL sanitization accepts unsafe URL attributes on iframe, object, and embed elements inserted through the clipboard or APIs. The attack requires a victim to load the stored content in an application embedding the editor, exposing data and actions available to that browser session.

The record

CVE
CVE-2024-21911
Published
Jan 3, 2024
Updated
Jul 14, 2026
Vendor
Tiny Technologies
Product
TinyMCE
Classifications
CWE-79, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 3, 2024CVE publishedPublication date reported by the CVE source.
  2. Jul 14, 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=0 <5.6.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Tiny Technologies · TinyMCEversion=0 <5.6.0

Published CVSS scores

6.1NISTCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
6.1CISA-ADPCVSS: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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1203Exploitation for Client Execution

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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