---
title: "CVE-2026-34571: CI4MS: Stored Cross‑Site Scripting (Stored XSS) in Backend User Management Allows Session Hijacking and Full Administrative Account Compromise"
url: https://erroneo.us/security/cve/CVE-2026-34571/
description: "CVE-2026-34571 (ci4-cms-erp/ci4ms (Composer (PHP))): CI4MS is a CodeIgniter 4-based CMS skeleton that delivers a production-ready, modular architecture with…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-04-01
date_modified: 2026-04-06
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-34571"
kev: false
cvss: 10
epss: 0.00561
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-34571: CI4MS: Stored Cross‑Site Scripting (Stored XSS) in Backend User Management Allows Session Hijacking and Full Administrative Account Compromise

**Signal:** Critical, preconditions apply. Severe if exploited, but exploitation needs conditions that may not apply to you. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- Not in CISA KEV , but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
- EPSS 0.6% , percentile 46: FIRST’s model estimates a 0.6% chance of exploitation activity in the next 30 days, higher than 46% of all scored CVEs (low). EPSS is a probability, not a verdict.
- Needs an account (low (any account)). Exposure depends on who can log in.
- Only applies if your dependency tree includes ci4-cms-erp/ci4ms (Composer (PHP)) <= 0.28.6.0, fixed in 0.31.0.0 . Check your lockfile, including transitive dependencies.

## What it is

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, a Stored Cross-Site Scripting (Stored XSS) vulnerability exists in the backend user management functionality. The application fails to properly sanitize user-controlled input before rendering it in the administrative interface, allowing attackers to inject persistent JavaScript code. This results in automatic execution whenever backend users access the affected page, enabling session hijacking, privilege escalation, and full administrative account compromise. This issue has been patched in version 0.31.0.0.

## Affected packages

- Composer (PHP) `ci4-cms-erp/ci4ms` <= 0.28.6.0 → fixed: 0.31.0.0

## Affected products (CVE record)

- ci4-cms-erp ci4ms: < 0.31.0.0

## Severity

- GitHub_M CVSS 3.1: 10 `CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H`
- GitHub CVSS 3.1: 9.9 `CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation poc , automatable no , technical impact total .
- FIRST EPSS (model of 2026-10-21): 0.56% probability of exploitation activity in the next 30 days; percentile 46.

## Sources

- [GitHub Advisory GHSA-fc4p-p49v-r948](https://github.com/advisories/GHSA-fc4p-p49v-r948)
- [CVE.org record CVE-2026-34571](https://www.cve.org/CVERecord?id=CVE-2026-34571)
- [NVD entry CVE-2026-34571](https://nvd.nist.gov/vuln/detail/CVE-2026-34571)
- [github.com](https://github.com/ci4-cms-erp/ci4ms/security/advisories/GHSA-fc4p-p49v-r948)
- [github.com](https://github.com/ci4-cms-erp/ci4ms/releases/tag/0.31.0.0)

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Source page: https://erroneo.us/security/cve/CVE-2026-34571/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt