What is CVE-2023-45818?

CVE-2023-45818 is a medium-severity vulnerability in Tiny Tinymce, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2023-10-19.

How severe is CVE-2023-45818?

Medium severity. CVSS v3 base score is 6.1 out of 10.

XSS in Tiny Tinymce

CVE-2023-45818

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.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2023-10-19 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.006 (47.6th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 48th percentile — 47.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.006 · newest: 0.006 · change: 0.000

Affected products

Tiny Tinymce
Tinymce — versions < 5.10.8, >= 6.0.0, < 6.7.1

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

github.com/tinymce/tinymce/security/advisories/GHSA-v65r-p3vv-jjfv (Vendor Advisory)
researchgate.net/publication/266654651_mXSS_attacks_Attacking_well-secured_web-… (Third Party Advisory)
tiny.cloud/docs/release-notes/release-notes5108/ (Release Notes)
tiny.cloud/docs/tinymce/6/6.7.1-release-notes/ (Release Notes)
www.tiny.cloud/docs/api/tinymce.html/tinymce.html.saxparser/ (Product)

Frequently asked questions

What is CVE-2023-45818?: CVE-2023-45818 is a medium-severity vulnerability in Tiny Tinymce, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2023-10-19.
How severe is CVE-2023-45818?: Medium severity. CVSS v3 base score is 6.1 out of 10.