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Unrestricted File UploadWeakness · CWE-434

CVE-2026-41587

HIGH · 8.6 CVSS v4.0 Published 2026-05-07
Patch available
A vendor patch is available. No clean upgrade release — apply the published patch.
See remediation →
92/100
Remediation priority · Urgent
Remotely reachable Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
CI4MS is a CodeIgniter 4-based CMS skeleton that delivers a production-ready, modular architecture with RBAC authorization and theme support. From version 0.26.0.0 to before version 0.31.7.0, 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. This issue has been patched in version 0.31.7.0.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis
How this class of weakness works · CWE-434

The application accepts uploaded files without properly checking their type or content, so an attacker can upload something executable. If it lands where the server will run it, that is remote code execution. Remediating it means validating content rather than just the extension, storing uploads outside the web root, and never executing them.

General guidance for the unrestricted file upload class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
High
Authentication
X
User interaction
None
Scope
X

CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Patch available Apply the vendor patch
Vendor patch github.com →
Recommended fix High confidence

version 0.31.7.0 or later

  1. Backup the current CI4MS installation including all files and database
  2. Download version 0.31.7.0 or later from the official CI4MS repository
  3. Replace the existing CI4MS files with the new version, preserving custom configurations
  4. If using custom themes, manually migrate them ensuring no raw PHP files are included
  5. Restore any custom configuration files from the backup
  6. Test the theme upload feature to confirm PHP files are now properly filtered/blocked
  7. Verify the application functions normally after the upgrade

Generated from the published advisory — verify against the referenced sources before acting.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-41587 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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