CVE-2023-45818: Tinymce Cross-Site Scripting Vulnerability

MODERATE
Advisory Identifier: GHSA-v65r-p3vv-jjfv
CVSS 6.1
CWE-79
Published
Advisory Summary

CVE-2023-45818 is a MODERATE (CVSS 6.1) cross-site scripting vulnerability (CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')) affecting Tinymce libraries in the npm ecosystem. The issue involves tinymce mxss vulnerability in undo/redo, getcontent api, resetcontent api, and autosave plugin. Remediation is available by upgrading affected packages to version 6.7.1, 5.10.8.

CVE-2023-45818 at a Glance

CVE Identifier CVE-2023-45818
GHSA Identifier GHSA-v65r-p3vv-jjfv
Severity MODERATE
CVSS v3.1 Base Score 6.1
CWE Classification CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Affected Product Tinymce
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 6.1

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction Required (UI:R)
Scope Changed (S:C)
Confidentiality Low (C:L)
Integrity Low (I:L)
Availability None (A:N)

How to Fix CVE-2023-45818

To remediate this vulnerability, upgrade all affected Tinymce dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

tinymce fixed: 6.7.1
npm install tinymce@6.7.1
TinyMCE fixed: 6.7.1
Upgrade TinyMCE to 6.7.1
tinymce/tinymce fixed: 6.7.1
Upgrade tinymce/tinymce to 6.7.1
tinymce fixed: 5.10.8
npm install tinymce@5.10.8
TinyMCE fixed: 5.10.8
Upgrade TinyMCE to 5.10.8
tinymce/tinymce fixed: 5.10.8
Upgrade tinymce/tinymce to 5.10.8
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release:

npm ls tinymce

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2023-45818, inspect your project dependencies using npm:

npm ls tinymce

Analyze the terminal output to locate any version of Tinymce in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 6.7.1), your application is affected.

Note: The npm ls tinymce command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting'), where the product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. In Tinymce, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### 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)

CVE-2023-45818 Affected Tinymce Versions

6 component(s)
Fixed Versions:
6.7.15.10.8
Product / Package Ecosystem Affected Versions Fixed Version
tinymce
npm
≥ 6.0.0
< 6.7.1
6.7.1
TinyMCE
NuGet
≥ 6.0.0
< 6.7.1
6.7.1
tinymce/tinymce
Packagist
≥ 6.0.0
< 6.7.1
6.7.1
tinymce
npm
< 5.10.8
5.10.8
TinyMCE
NuGet
< 5.10.8
5.10.8
tinymce/tinymce
Packagist
< 5.10.8
5.10.8

References

Frequently Asked Questions

What is CVE-2023-45818?
CVE-2023-45818 is a security vulnerability in Tinymce involving TinyMCE mXSS vulnerability in undo/redo, getContent API, resetContent API, and Autosave plugin under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting').
Which Tinymce versions are affected?
Affected versions include releases prior to 6.7.1, 5.10.8 across affected packages: tinymce, TinyMCE, tinymce/tinymce.
What version fixes CVE-2023-45818?
Upgrading to 6.7.1, 5.10.8 (or the latest patched release for your respective branch) resolves the vulnerability.
Is tinymce affected?
Yes, tinymce is affected in releases prior to 6.7.1, 5.10.8. Upgrade your dependency to 6.7.1, 5.10.8 or later.
Is TinyMCE affected?
Yes, TinyMCE is affected in releases prior to 6.7.1, 5.10.8. Upgrade your dependency to 6.7.1, 5.10.8 or later.
What is the CVSS score of CVE-2023-45818?
CVE-2023-45818 has a CVSS v3.1 base score of 6.1 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.
What CWE is associated with CVE-2023-45818?
CVE-2023-45818 is classified under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') (The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.).
How can I check npm dependencies for CVE-2023-45818?
Run the dependency tree command: 'npm ls tinymce'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-v65r-p3vv-jjfv",
  "modified" : "2023-11-15T23:24:58Z",
  "published" : "2023-10-19T16:36:29Z",
  "aliases" : [ "CVE-2023-45818" ],
  "summary" : "TinyMCE mXSS vulnerability in undo/redo, getContent API, resetContent API, and Autosave plugin",
  "details" : "### Impact\nA [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.\n​This vulnerability also impacts these related TinyMCE APIs and plugins:​\n* [`tinymce.Editor.getContent({ format: 'raw' })`](https://tiny.cloud/docs/tinymce/6/apis/tinymce.editor/#getContent)\n* [`tinymce.Editor.resetContent()`](https://tiny.cloud/docs/tinymce/6/apis/tinymce.editor/#resetContent)\n* [Autosave Plugin](https://tiny.cloud/docs/tinymce/6/autosave/)\n\n### Patches\nThis 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.\n\n### Fix\nTo avoid this vulnerability:\n* Upgrade to TinyMCE 5.10.8 or higher for TinyMCE 5.x.\n* Upgrade to TinyMCE 6.7.1 or higher for TinyMCE 6.x.\n\n### Acknowledgements\nTiny Technologies would like to thank Masato Kinugawa of [Cure53](https://cure53.de/) for discovering this vulnerability.\n\n### References\n* [TinyMCE 5.10.8 Release Notes](https://tiny.cloud/docs/release-notes/release-notes5108/)\n* [TinyMCE 6.7.1 Release Notes](https://tiny.cloud/docs/tinymce/6/6.7.1-release-notes/)\n\n### For more information\nIf you have any questions or comments about this advisory:\n* Email us at <infosec@tiny.cloud>\n* Open an issue in the [TinyMCE repo](https://github.com/tinymce/tinymce/issues?q=is%3Aissue+is%3Aopen+sort%3Aupdated-desc)",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N"
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  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2023-45818"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/tinymce/tinymce"
  }, {
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    "url" : "https://researchgate.net/publication/266654651_mXSS_attacks_Attacking_well-secured_web-applications_by_using_innerHTML_mutations"
  }, {
    "type" : "WEB",
    "url" : "https://tiny.cloud/docs/release-notes/release-notes5108/#securityfixes"
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  }, {
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    "url" : "https://www.tiny.cloud/docs/api/tinymce.html/tinymce.html.saxparser"
  } ],
  "database_specific" : {
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    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2023-10-19T16:36:29Z",
    "nvd_published_at" : "2023-10-19T22:15:10Z"
  }
}