CVE-2026-34558 CI4MS: Methods Management Full Account Takeover for All-Roles & Privilege-Escalation via Stored DOM XSS

Critical 9.1 Published 30 Mar 2026 Updated 31 Mar 2026

Attackers can execute stored DOM XSS in CI4MS to achieve full account takeover and privilege escalation via unsanitized input in Methods Management.

Exploited in the wild: Not known
Login needed: Any signed-in user
Attackable: Over the internet
Victim action needed: Not needed
Fix: Available

What is CVE-2026-34558?

CVE-2026-34558 is a critical cross-site scripting vulnerability in ci4-cms-erp ci4ms, published on 30 Mar 2026. Any signed-in user can exploit it over the network, with no action from the victim.

Official description

CI4MS is a CodeIgniter 4-based CMS skeleton that delivers a production-ready, modular architecture with RBAC authorization and theme support. Prior to version 0.31.0.0, the application fails to properly sanitize user-controlled input within the Methods Management functionality when creating or managing application methods/pages. Multiple input fields accept attacker-controlled JavaScript payloads that are stored server-side without sanitization or output encoding. These stored values are later rendered directly into administrative interfaces and global navigation components without proper encoding, resulting in Stored DOM-Based Cross-Site Scripting (XSS). This issue has been patched in version 0.31.0.0.

Weakness: CWE-79

Which versions are affected by CVE-2026-34558?

2 open source packages ship an affected version, including ci4-cms-erp/ci4ms. It affects 1 product.

Package	Affected	Fixed in
`ci4-cms-erp/ci4ms` Packagist	All versions	`0.31.0.0`
`ci4-cms-erp/ci4ms` Packagist	All versions	`0.31.0.0`

Products include Ci4-Cms-Erp Ci4ms.

How do I fix CVE-2026-34558?

Upgrade ci4-cms-erp/ci4ms to 0.31.0.0 or later.

Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.

Is CVE-2026-34558 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-34558 exists.

Sources

Also known as GHSA-v77r-xg3p-75g7.