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Medium, CVSS 5.4

Silverstripe has Cross-site Scripting (XSS) vulnerabilities inherited from TinyMCE

GHSA-4q66-g4mm-8rg5

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (silverstripe/admin 1.13.6), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
5.4 · CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N
EPSS
No dated EPSS signal available.
Source description

As published by the source; long descriptions are shortened.

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: - GHSA-5h9g-x5rv-25wg Cross-site scripting vulnerability in TinyMCE - GHSA-w7jx-j77m-wp65 Cross-site scripting vulnerability in TinyMCE

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 1 · created ·

    Published from ghsa record GHSA-4q66-g4mm-8rg5

Agent brief

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: GHSA-4q66-g4mm-8rg5

Advisory: Silverstripe has Cross-site Scripting (XSS) vulnerabilities inherited from TinyMCE
IDs: GHSA-4q66-g4mm-8rg5
Record: https://patchnext.com/advisories/ghsa-4q66-g4mm-8rg5 (revision 1, source checked 26 Oct 2026, 14:06 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.4)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: silverstripe/admin 1.13.6. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist silverstripe/admin: affected < 1.13.6; fixed in 1.13.6

## Suggested inspection (read-only)
- Packagist silverstripe/admin: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on silverstripe/admin.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-4q66-g4mm-8rg5 (GitHub-reviewed advisory GHSA-4q66-g4mm-8rg5 lists affected ranges: Packagist silverstripe/admin >=0 <1.13.6)

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