# CVE-2026-39391: CI4MS has Stored XSS via Unescaped Blacklist Note in Admin User List

> An admin can inject JavaScript via blacklist notes that executes in other admins' browsers, potentially leading to account takeover.

- **Severity:** Medium 4.8 (`CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 8 Apr 2026
- **Updated:** 8 Apr 2026
- **Also known as:** GHSA-7cm9-v848-cfh2

## What is CVE-2026-39391?

CVE-2026-39391 is a medium-severity cross-site scripting vulnerability in ci4-cms-erp ci4ms, published on 8 Apr 2026. An attacker needs administrator access to exploit it, and only if a user opens a file or follows a link.

### 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 0.31.4.0, the blacklist (ban) note parameter in UserController::ajax_blackList_post() is stored in the database without sanitization and rendered into an HTML data-note attribute without escaping. An admin with blacklist privileges can inject arbitrary JavaScript that executes in the browser of any other admin who views the user management page. This vulnerability is fixed in 0.31.4.0.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2026-39391?

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


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `ci4-cms-erp/ci4ms` | Packagist | All versions | 0.31.4.0 |
| `ci4-cms-erp/ci4ms` | Packagist | All versions | 0.31.4.0 |

Products: Ci4-Cms-Erp Ci4ms.

## How do I fix CVE-2026-39391?

Upgrade ci4-cms-erp/ci4ms to 0.31.4.0 or later.

## Is CVE-2026-39391 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-39391 exists.

## Other vulnerabilities in ci4-cms-erp ci4ms

- [CVE-2026-34569](https://insights.sbomify.com/CVE-2026-34569/): CI4MS: Blogs Categories Full Account Takeover for All-Roles & Privilege-Escalation via Stored DOM XSS (critical 10.0)
- [CVE-2026-34571](https://insights.sbomify.com/CVE-2026-34571/): CI4MS: Stored Cross‑Site Scripting (Stored XSS) in Backend User Management Allows Session Hijacking and Full Administrative Account Compromise (critical 10.0)
- [CVE-2026-25510](https://insights.sbomify.com/CVE-2026-25510/): CI4MS Vulnerable to Remote Code Execution (RCE) via Arbitrary File Creation and Save in File Editor (critical 10.0)
- [CVE-2026-34989](https://insights.sbomify.com/CVE-2026-34989/): CI4MS: Profile & User Management Full Account Takeover for All-Roles & Privilege-Escalation via Stored DOM XSS (critical 9.4)
- [CVE-2026-34559](https://insights.sbomify.com/CVE-2026-34559/): CI4MS: Blogs Tags Full Account Takeover for All-Roles & Privilege-Escalation via Stored DOM XSS (critical 9.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-39391 and fix it if it is affected.

What it is: CVE-2026-39391 is a medium-severity cross-site scripting vulnerability in ci4-cms-erp ci4ms, published on 8 Apr 2026. An attacker needs administrator access to exploit it, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-39391 exists.

Affected packages and fixed versions:
- ci4-cms-erp/ci4ms (Packagist): affected all versions; fixed in 0.31.4.0
- ci4-cms-erp/ci4ms (Packagist): affected all versions; fixed in 0.31.4.0

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-39391/ (Markdown: https://insights.sbomify.com/CVE-2026-39391/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-39391
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-39391
- OSV: https://osv.dev/vulnerability/CVE-2026-39391

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-39391/
Summaries are generated and may contain mistakes; the official description above is the record.