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TinymceApplication · Tiny

CVE-2023-45818

MEDIUM · 6.1 CVSS v3.1 Published 2023-10-19
Fix available
A fix is available. Upgrade to 5.10.8 / 6.7.1 or later.
See remediation →
68/100
Remediation priority · Elevated
Remotely reachable No privileges

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
TinyMCE is an open source rich text editor. A mutation cross-site scripting (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 (TinyMCE 5) mutates the HTML maliciously, allowing an XSS payload to be executed. 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. Users are advised to upgrade. There are no known workarounds for this vulnerability.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

TinyMCE contains a mutation XSS vulnerability in its undo/redo functionality. When HTML passes XSS sanitization but is then manipulated as a string by internal trimming functions before storage in the undo stack, restoration from the undo stack combined with reparative parsing mutates the HTML maliciously, allowing XSS execution.

MitigationUpgrade TinyMCE to version 5.10.8 or higher (for TinyMCE 5) or 6.7.1 or higher (for TinyMCE 6). No workarounds exist.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
TinymceApplication
Affected:< 5.10.8>= 6.0.0, < 6.7.1

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify TinyMCE version in use
    Check your application's JavaScript dependencies (package.json, node_modules, or loaded scripts) for the tinymce version, or inspect the loaded TinyMCE script and look for the version string in the source (often in tinymce.min.js: search for 'version:' or 'ver=')
    Affected if The installed version is below 5.10.8, or is 6.0.0 through 6.7.0
  2. Confirm undo/redo is available
    Verify the TinyMCE editor instance has undo and redo buttons in the toolbar, or check the editor configuration for 'undo' plugin inclusion (it is bundled in the default preset but can be excluded via 'toolbar' or 'plugins' settings)
    Affected if The undo/redo functionality is present and enabled in the editor configuration
  3. Determine if HTML content editing occurs
    Review the editor's mode configuration - check if 'mode' is set to 'design' (default) or 'readonly' is false, and verify the editor is used for HTML-formatted content (not plain text only)
    Affected if The editor processes and stores HTML content that could be manipulated through the undo/redo mechanism

You are affected if your TinyMCE version falls within the vulnerable range (< 5.10.8 or 6.0.0-6.7.0) and the undo/redo feature is enabled while processing HTML content.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 5.10.8 / 6.7.1 or later
Fixed in 5.10.86.7.1
Interim mitigation

Upgrade TinyMCE to version 5.10.8 or higher (for TinyMCE 5) or 6.7.1 or higher (for TinyMCE 6). No workarounds exist.

Recommended fix High confidence

TinyMCE 5.10.8 (for 5.x users) or TinyMCE 6.7.1 (for 6.x users)

  1. Identify the current TinyMCE version in use by checking the JavaScript file or package.json dependency
  2. If using TinyMCE 5.x (versions < 5.10.8), upgrade to version 5.10.8
  3. If using TinyMCE 6.x (versions >= 6.0.0 and < 6.7.1), upgrade to version 6.7.1
  4. Update the TinyMCE script reference or npm/yarn package dependency to the appropriate fixed version
  5. Clear any cached versions of TinyMCE in the application
  6. Test the editor functionality including undo/redo operations in a staging environment
  7. Deploy the updated version to production
Caveat Review TinyMCE changelogs between your current version and the target version for any breaking changes in the minor/major release

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Tinymce Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing6.0 h
  • Review / QA2.0 h
12.0 hours of engineering $2,020
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Scan for this in your stack

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2023-45818 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data