Unrestricted File UploadWeakness · CWE-434

CVE-2026-48062

CRITICAL · 9.8 CVSS v3.1 Published 2026-07-17
No fix yet
No fix has been published. The vendor has not shipped a fixed release or patch. You remain exposed.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click 5 weeks old

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
CodeIgniter is a PHP full-stack web framework. Prior to 4.7.3, the ext_in upload validation rule in system/Validation/StrictRules/FileRules.php checked the MIME-derived guessed extension instead of the client-provided filename extension. As a result, an uploaded file named shell.php containing GIF-like content could pass validation such as uploaded[avatar]|is_image[avatar]|mime_in[avatar,image/gif]|ext_in[avatar,gif] because the detected MIME type maps to gif, even though the uploaded filename extension is php. Applications are impacted if they accept user-controlled uploads, rely on ext_in to validate the uploaded filename extension, save uploaded files using the original client filename with $file->move($path), store uploads in a web-accessible directory, and allow PHP or other executable files to run from that directory. In those conditions, this may lead to arbitrary code execution. This issue is fixed in version 4.7.3.

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
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

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
Recommended fix High confidence

4.7.3

  1. 1. Create a full backup of your CodeIgniter application including the system directory, application directory, and any uploaded files.
  2. 2. Update your CodeIgniter installation to version 4.7.3. If using Composer, run: composer update codeigniter4/framework
  3. 3. Alternatively, manually download CodeIgniter 4.7.3 from the official repository and replace the system/ directory.
  4. 4. Clear any cached files, temporary directories, or opcode caches.
  5. 5. Test your file upload functionality to ensure ext_in validation now correctly checks the client-provided filename extension rather than the MIME-derived extension.
  6. 6. Verify that uploaded files are still being handled as expected by your application.
  7. 7. If you were using the vulnerable validation pattern (ext_in), confirm it now properly rejects files like shell.php even if their MIME type matches the allowed extension.
Caveat Minor version upgrades in CodeIgniter typically include security fixes without breaking changes, but review the changelog for any deprecation notices

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

No vendor fix exists The vendor has not published a patch for this.

There is no version to upgrade to and no patch to apply. Every affected install stays exposed until the vendor ships a fix — or somebody else builds one.

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Free · runs locally
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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-2026-48062 in production — separate from our analysis above.

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