CVE-2026-34564 is a critical stored cross-site scripting flaw in CI4MS, a CodeIgniter 4 based CMS. NVD scores it 9.1. Page data added to navigation menus through Menu Management is stored and rendered without output encoding in admin screens and public menus. Upgrade to ci4ms 0.31.0.0 or later.
What's affected
CI4MS (ci4-cms-erp ci4ms) versions before 0.31.0.0. The fixed release is 0.31.0.0.
Any site running an older build with the affected feature reachable to a signed in user is in scope.
How to check if you're exposed
Find the ci4ms version your site runs. If you deployed from a git checkout, git describe --tags in the project folder shows the nearest release tag. Otherwise look at the release or commit you installed from.
Anything older than 0.31.0.0 is in scope. The record names no workaround, so the version number is the test. The advisory linked under Sources lists the exact affected range.
What to do now
- Upgrade ci4ms to 0.31.0.0 or later and redeploy.
- Until you can, limit who holds accounts that can manage menus, and review those accounts.
- Look through existing menu entries for entries that contain script tags or event handler attributes, and clean them.
- Sign out active sessions for administrators after the upgrade.
Why it matters
The weakness class is CWE-79, cross-site scripting. The record describes a stored DOM based XSS: page related data selected in Menu Management is stored and rendered into administrative interfaces and public navigation menus without encoding.
Stored XSS is worse than the reflected kind because the script waits in the database and runs for every person who later opens the page. The CVSS vector has Scope Changed, which reflects that the script runs in the browser of someone else, often an administrator. The usual fix is output encoding on every place the stored value is rendered, plus input validation.
The record does not flag this CVE as listed in CISA's Known Exploited Vulnerabilities catalog, and the advisory I read does not say it is exploited.
Quick check
What is the difference between DOM XSS and plain stored XSS?
In DOM based XSS, client side script reads a stored value and writes it into the page unsafely. The data is stored on the server in both cases, but the unsafe step happens in the browser.
Sources
Last reviewed: 19 October 2026.
