Summary
Silverstripe has Cross-site Scripting (XSS) vulnerabilities inherited from TinyMCE
TinyMCE 4.x is vulnerable to several XSS vectors, which had been patched in later versions. Two of these have been identified as affecting silverstripe/admin.
Only Silverstripe CMS 4 is affected by this issue. It's not possible to upgrade Silverstripe CMS 4 to use a more recent release of TinyMCE without introducing breaking changes. Instead, the security patches that shipped in later releases of TinyMCE have been backported to the TinyMCE version bundled in silverstripe/admin.
Silverstripe CMS 5 is not affected by those vulnerabilities because it uses TinyMCE 6.
You can find more information about the underlying vulnerabilities in those GitHub security advisories:
Impact
GHSA-4Q66-G4MM-8RG5 has a CVSS score of 5.4 (Medium). The vector is network-reachable, no privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.13.6); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Already deployed Kodem?
See it in your environmentNew to Kodem? Get a demo →Remediation advice
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
Frequently Asked Questions
- What is GHSA-4Q66-G4MM-8RG5? GHSA-4Q66-G4MM-8RG5 is a medium-severity security vulnerability in silverstripe/admin (composer), affecting versions < 1.13.6. It is fixed in 1.13.6.
- How severe is GHSA-4Q66-G4MM-8RG5? GHSA-4Q66-G4MM-8RG5 has a CVSS score of 5.4 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of silverstripe/admin are affected by GHSA-4Q66-G4MM-8RG5? silverstripe/admin (composer) versions < 1.13.6 is affected.
- Is there a fix for GHSA-4Q66-G4MM-8RG5? Yes. GHSA-4Q66-G4MM-8RG5 is fixed in 1.13.6. Upgrade to this version or later.
- Is GHSA-4Q66-G4MM-8RG5 exploitable, and should I be worried? Whether GHSA-4Q66-G4MM-8RG5 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether GHSA-4Q66-G4MM-8RG5 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix GHSA-4Q66-G4MM-8RG5? Upgrade
silverstripe/adminto 1.13.6 or later.