CVE-2024-21908Network attack vector

Stored XSS via core-parser validation bypass

Published Jan 3, 2024 · Updated Jul 14, 2026

Stored cross-site scripting in TinyMCE before 5.9.0 allows remote attackers to execute JavaScript in another user's browser. The core parser unwraps invalid elements without reapplying schema validation, allowing crafted content inserted through clipboard or editor APIs to retain executable markup. Execution requires another user to render the stored content, and publication outside the editor is exposed when server-side sanitization is absent.

CVSS severity6.1
Medium
EPSS probability1.07%
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 5.9.0 allows remote attackers to execute JavaScript in another user's browser. The core parser unwraps invalid elements without reapplying schema validation, allowing crafted content inserted through clipboard or editor APIs to retain executable markup. Execution requires another user to render the stored content, and publication outside the editor is exposed when server-side sanitization is absent.

The record

CVE
CVE-2024-21908
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 <5.9.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Tiny Technologies · TinyMCEversion=0 <5.9.0

Published CVSS scores

6.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
6.1Tiny TechnologiesCVSS: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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