CVE-2023-45818 — TinyMCE mXSS vulnerability in TinyMCE — CVE Details

MEDIUM

TinyMCE mXSS vulnerability in undo/redo, getContent API, resetContent API, and Autosave plugin

Published October 19, 2023Updated September 10, 2026Source: osv

Summary

### Impact A [mutation cross-site scripting](https://researchgate.net/publication/266654651_mXSS_attacks_Attacking_well-secured_web-applications_by_using_innerHTML_mutations) (mXSS) vulnerability was discovered in TinyMCE’s core undo and redo functionality. When a carefully-crafted HTML snippet passes the XSS sanitisation layer, it is manipulated as a string by internal trimming functions before being stored in the undo stack. If the HTML snippet is restored from the undo stack, the combination of the string manipulation and reparative parsing by either the browser's native [DOMParser API](https://developer.mozilla.org/en-US/docs/Web/API/DOMParser) (TinyMCE 6) or the [SaxParser API](https://www.tiny.cloud/docs/api/tinymce.html/tinymce.html.saxparser/) (TinyMCE 5) mutates the HTML maliciously, allowing an XSS payload to be executed. This vulnerability also impacts these related TinyMCE APIs and plugins: * [`tinymce.Editor.getContent({ format: 'raw' })`](https://tiny.cloud/docs/tinymce/6/apis/tinymce.editor/#getContent) * [`tinymce.Editor.resetContent()`](https://tiny.cloud/docs/tinymce/6/apis/tinymce.editor/#resetContent) * [Autosave Plugin](https://tiny.cloud/docs/tinymce/6/autosave/) ### Patches This vulnerability has been patched in TinyMCE 5.10.8 and TinyMCE 6.7.1 by ensuring HTML is trimmed using node-level manipulation instead of string manipulation. ### Fix To avoid this vulnerability: * Upgrade to TinyMCE 5.10.8 or higher for TinyMCE 5.x. * Upgrade to TinyMCE 6.7.1 or higher for TinyMCE 6.x. ### Acknowledgements Tiny Technologies would like to thank Masato Kinugawa of [Cure53](https://cure53.de/) for discovering this vulnerability. ### References * [TinyMCE 5.10.8 Release Notes](https://tiny.cloud/docs/release-notes/release-notes5108/) * [TinyMCE 6.7.1 Release Notes](https://tiny.cloud/docs/tinymce/6/6.7.1-release-notes/) ### For more information If you have any questions or comments about this advisory: * Email us at <infosec@tiny.cloud> * Open an issue in the [TinyMCE repo](https://github.com/tinymce/tinymce/issues?q=is%3Aissue+is%3Aopen+sort%3Aupdated-desc)

Advisory Timeline

First published October 19, 2023 (1089 days ago).
Last revised September 10, 2026 — 1056 days after initial publication.

Remediation

Upgrade to the fixed version using your package manager.

NuGet

Update TinyMCE to 5.10.8 or later

dotnet add package TinyMCE --version 5.10.8

npm

Update tinymce to 6.7.1 or later

npm install tinymce@6.7.1

NuGet

Update TinyMCE to 6.7.1 or later

dotnet add package TinyMCE --version 6.7.1

Composer

Update tinymce/tinymce to 5.10.8 or later

composer require "tinymce/tinymce:^5.10.8"

Composer

Update tinymce/tinymce to 6.7.1 or later

composer require "tinymce/tinymce:^6.7.1"

npm

Update tinymce to 5.10.8 or later

npm install tinymce@5.10.8

After upgrading, run your dependency scanner again to confirm the vulnerability is resolved.

Affected Packages (6)

Affects 3 ecosystems: npm (1), nuget (1), packagist (1).

Package	Ecosystem	Affected	Fixed In
TinyMCE	nuget	3.4.3.2, 3.4.4, 3.4.5, 3.4.7 (+176 more)	5.10.8
tinymce	npm	All versions	6.7.1
TinyMCE	nuget	6.0.0, 6.0.1, 6.0.2, 6.0.3 (+14 more)	6.7.1
tinymce/tinymce	packagist	4.0.0, 4.0.1, 4.0.10, 4.0.11 (+167 more)	5.10.8
tinymce/tinymce	packagist	6.0.0, 6.0.1, 6.0.2, 6.0.3 (+16 more)	6.7.1
tinymce	npm	All versions	5.10.8

Vulnerability Classification

Common Weakness Enumeration (CWE) identifiers for this vulnerability type.

CWE-79
Cross-site Scripting (XSS)MITRE

CVSS Score Breakdown

What the CVSS (Common Vulnerability Scoring System) 6.1 score means for each attack dimension.

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

Required

Scope

Changed

Confidentiality

Low

Integrity

Low

Availability

None

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

References

Frequently Asked Questions

What is CVE-2023-45818?: TinyMCE mXSS vulnerability in undo/redo, getContent API, resetContent API, and Autosave plugin This vulnerability has been assigned a severity rating of MEDIUM (CVSS score: 6.1/10).
How do I check if my project is affected by CVE-2023-45818?: CVE-2023-45818 affects TinyMCE, tinymce and tinymce/tinymce. Use GeekWala's free vulnerability scanner to check your dependencies against CVE-2023-45818 and 200,000+ other known vulnerabilities.

Severity & Exploitability

CVSS Score

6.1

Exploitation requires specific conditions or has limited impact. Remediate within weeks.

Also Known As

GHSA-v65r-p3vv-jjfv

Related CVEs

CVE-2026-47760
HIGH
TinyMCE Cross-Site Scripting (XSS) vulnerability using sanitization bypass through nested SVGs
CVE-2026-47759
HIGH
TinyMCE Cross-Site Scripting (XSS) vulnerability using through data-mce- prefixed src, href, style attributes
CVE-2024-21908
MEDIUM
Cross-site scripting vulnerability in TinyMCE
CVE-2024-38356
MEDIUM
TinyMCE Cross-Site Scripting (XSS) vulnerability using noneditable_regexp option
CVE-2022-23494
MEDIUM
Cross-site scripting vulnerability in TinyMCE alerts
CVE-2023-45819
MEDIUM
TinyMCE XSS vulnerability in notificationManager.open API
CVE-2024-21910
MEDIUM
Cross-site scripting vulnerability in TinyMCE plugins
CVE-2023-48219
MEDIUM
TinyMCE vulnerable to mutation Cross-site Scripting via special characters in unescaped text nodes

Check if you're affected

Scan your dependencies to see if this vulnerability affects your projects.

Scan Your Dependencies