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 (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.
CVE-2023-45818
MEDIUMNVD 6.16.1—
EchelonGraph scoreMEDIUM confidence
This medium-severity CVE scores 6.1 under NVD CVSS v3. EPSS exploit probability: 1.3%, top 20% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
Triggered by: NVD CVSS baseline
Sources: epss, nvd
6.1
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
- Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 1%CVSS: 6.1Exploit: NoneExposed: 0
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 6.1
- EG Score
- 6.1(medium)
- EPSS
- 45.5%
- KEV
- Not listed
Published
October 19, 2023
Last Modified
June 17, 2026
References (10)
- security-advisories@githubhttps://github.com/tinymce/tinymce/security/advisories/GHSA-v65r-p3vv-jjfv
- security-advisories@githubhttps://researchgate.net/publication/266654651_mXSS_attacks_Attacking_well-secured_web-applications_by_using_innerHTML_mutations
- security-advisories@githubhttps://tiny.cloud/docs/release-notes/release-notes5108/#securityfixes
- security-advisories@githubhttps://tiny.cloud/docs/tinymce/6/6.7.1-release-notes/#security-fixes
- security-advisories@githubhttps://www.tiny.cloud/docs/api/tinymce.html/tinymce.html.saxparser/
- af854a3a-2127-422b-91ae-364da2661108https://github.com/tinymce/tinymce/security/advisories/GHSA-v65r-p3vv-jjfv
- af854a3a-2127-422b-91ae-364da2661108https://researchgate.net/publication/266654651_mXSS_attacks_Attacking_well-secured_web-applications_by_using_innerHTML_mutations
- af854a3a-2127-422b-91ae-364da2661108https://tiny.cloud/docs/release-notes/release-notes5108/#securityfixes
- af854a3a-2127-422b-91ae-364da2661108https://tiny.cloud/docs/tinymce/6/6.7.1-release-notes/#security-fixes
- af854a3a-2127-422b-91ae-364da2661108https://www.tiny.cloud/docs/api/tinymce.html/tinymce.html.saxparser/
Affected Packages
(3 across 3 ecosystems)
npm(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| tinymce | — | 5.10.8 | — |
NuGet(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| TinyMCE | 3.4.3.2 ... 5.9.2 (180 versions) | 5.10.8 | — |
Packagist(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| tinymce/tinymce | 4.0.0 ... 5.9.2 (171 versions) | 5.10.8 | — |
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Frequently asked(5)
What is CVE-2023-45818?
CVE-2023-45818 is a medium vulnerability published on October 19, 2023. 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…
When was CVE-2023-45818 disclosed?
CVE-2023-45818 was first published in the National Vulnerability Database on October 19, 2023, with the most recent update on June 17, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2023-45818 actively exploited?
CVE-2023-45818 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 45.5% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2023-45818?
CVE-2023-45818 has a CVSS v3 base score of 6.1 (NVD).
How do I remediate CVE-2023-45818?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2023-45818, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2023-45818
Is Your Infrastructure Affected by CVE-2023-45818?
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