CVE-2026-63223: CodeIgniter Uploaded File Extension Validation Bypass Vulnerability

CRITICAL
Advisory Identifier: GHSA-mmj4-63m4-r6h5
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CVSS 9.8
CWE-434
Published
Advisory Summary

CVE-2026-63223 is a CRITICAL (CVSS 9.8) uploaded file extension validation bypass vulnerability (CWE-434: Unrestricted Upload of File with Dangerous Type) affecting CodeIgniter libraries in the Packagist ecosystem. The issue involves uploaded file extension validation bypass in `is_image` and `mime_in` rules. Remediation is available by upgrading affected packages to version 4.7.4.

CVE-2026-63223 at a Glance

CVE Identifier CVE-2026-63223
GHSA Identifier GHSA-mmj4-63m4-r6h5
Severity CRITICAL
CVSS v3.1 Base Score 9.8
CWE Classification CWE-434: Unrestricted Upload of File with Dangerous Type
Affected Product CodeIgniter
Package Ecosystem Packagist
Published Date
Last Updated

Security Impact

CVSS: 9.8

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality High (C:H)
Integrity High (I:H)
Availability High (A:H)

How to Fix CVE-2026-63223

To remediate this vulnerability, upgrade all affected CodeIgniter dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

codeigniter4/framework fixed: 4.7.4 
Upgrade codeigniter4/framework to 4.7.4
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for codeigniter4/framework

How to Check if You Are Affected

To determine whether your application is affected by CVE-2026-63223, inspect your project dependencies for CodeIgniter:

inspect dependencies for codeigniter4/framework

Analyze the terminal output to locate any version of CodeIgniter in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 4.7.4), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-434: Unrestricted Upload of File with Dangerous Type, where the product allows the upload or transfer of dangerous file types that are automatically processed within its environment. In CodeIgniter, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### Impact This is an unsafe file upload validation vulnerability that can lead to remote code execution in vulnerable application configurations. Applications are impacted when they: - validate uploads using `is_image` or `mime_in` without an independent safe extension check, such as `ext_in` on patched versions - save uploaded files using the client-supplied filename - place uploads in a web-accessible directory where PHP files can execute ### Patches Upgrade to v4.7.4 or later. ### Workarounds - Save uploads outside the public web root, preferably under `writable/uploads`. - Use `$file->store()` or `$file->move($path, $file->getRandomName())` instead of preserving the original client filename. - Disable script execution in any public upload directory. - Manually verify the client filename extension before moving the file. - For image uploads, reject files when `$file->getClientExtension()` is not an allowed image extension. - For exact MIME-type validation, reject files when `$file->getClientExtension()` does not match `$file->guessExtension()`.

CVE-2026-63223 Affected CodeIgniter Versions

1 component(s)
Fixed Versions:
4.7.4
Product / Package Ecosystem Affected Versions Fixed Version
codeigniter4/framework
 Packagist
< 4.7.4
4.7.4

References

GitHub Advisory / Wiki ADVISORY
https://github.com/codeigniter4/CodeIgniter4/security/advisories/GHSA-mmj4-63m4-r6h5
NVD — CVE-2026-63223 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-63223
Security Fix Commit FIX COMMIT
https://github.com/codeigniter4/CodeIgniter4/commit/b6e9a4fa1dca2df3d3f261bdf61532df8c6420aa
CodeIgniter Source Repository REPOSITORY
https://github.com/codeigniter4/CodeIgniter4
CodeIgniter Release RELEASE
https://github.com/codeigniter4/CodeIgniter4/releases/tag/v4.7.4

Frequently Asked Questions

What is CVE-2026-63223?
CVE-2026-63223 is a security vulnerability in CodeIgniter involving Uploaded file extension validation bypass in `is_image` and `mime_in` rules under CWE-434: Unrestricted Upload of File with Dangerous Type.
Which CodeIgniter versions are affected?
Affected versions include releases prior to 4.7.4 across affected packages: codeigniter4/framework.
What version fixes CVE-2026-63223?
Upgrading to 4.7.4 (or the latest patched release for your respective branch) resolves the vulnerability.
Is codeigniter4/framework affected?
Yes, codeigniter4/framework is affected in releases prior to 4.7.4. Upgrade your dependency to 4.7.4 or later.
What is the CVSS score of CVE-2026-63223?
CVE-2026-63223 has a CVSS v3.1 base score of 9.8 (CRITICAL) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
What CWE is associated with CVE-2026-63223?
CVE-2026-63223 is classified under CWE-434: Unrestricted Upload of File with Dangerous Type (The product allows the upload or transfer of dangerous file types that are automatically processed within its environment.).
How can I check Packagist dependencies for CVE-2026-63223?
Run the dependency tree command: 'inspect dependencies for codeigniter4/framework'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-mmj4-63m4-r6h5",
  "modified" : "2026-08-07T18:24:21Z",
  "published" : "2026-08-07T18:24:21Z",
  "aliases" : [ "CVE-2026-63223" ],
  "summary" : "CodeIgniter: Uploaded file extension validation bypass in `is_image` and `mime_in` rules",
  "details" : "### Impact\nThis is an unsafe file upload validation vulnerability that can lead to remote code execution in vulnerable application configurations.\n\nApplications are impacted when they:\n- validate uploads using `is_image` or `mime_in` without an independent safe extension check, such as `ext_in` on patched versions\n- save uploaded files using the client-supplied filename\n- place uploads in a web-accessible directory where PHP files can execute\n\n### Patches\nUpgrade to v4.7.4 or later.\n\n### Workarounds\n- Save uploads outside the public web root, preferably under `writable/uploads`.\n- Use `$file->store()` or `$file->move($path, $file->getRandomName())` instead of preserving the original client filename.\n- Disable script execution in any public upload directory.\n- Manually verify the client filename extension before moving the file.\n- For image uploads, reject files when `$file->getClientExtension()` is not an allowed image extension.\n- For exact MIME-type validation, reject files when `$file->getClientExtension()` does not match `$file->guessExtension()`.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "codeigniter4/framework"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "4.7.4"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/codeigniter4/CodeIgniter4/security/advisories/GHSA-mmj4-63m4-r6h5"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-63223"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/codeigniter4/CodeIgniter4/commit/b6e9a4fa1dca2df3d3f261bdf61532df8c6420aa"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/codeigniter4/CodeIgniter4"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/codeigniter4/CodeIgniter4/releases/tag/v4.7.4"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-434" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-08-07T18:24:21Z",
    "nvd_published_at" : "2026-07-31T06:16:32Z"
  }
}