Arbitrary file upload in CodeIgniter4 - CVE-2026-63223
Published: July 7, 2026 / Updated: August 21, 2026
Vulnerability identifier: #VU137010
CSH Severity: High
CVSS v4: 9.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-63223
CWE-ID: CWE-434
Exploitation vector: Remote access
Exploit availability:
Public exploit is available
Vulnerability details
The vulnerability allows a remote attacker to execute arbitrary code.
The vulnerability exists due to unrestricted upload of file with dangerous type in the `is_image` and `mime_in` file upload validation rules when validating uploaded files. A remote attacker can upload a crafted file with a dangerous extension to execute arbitrary code.
Applications are impacted when uploaded files are saved using the client-supplied filename and placed in a web-accessible directory where PHP files can execute.
Affected software
CodeIgniter4
How to mitigate CVE-2026-63223
Install security update from vendor's website.
CodeIgniter4 - update to 4.7.4
Links to Public Exploits and PoC-codes
- Exploit #12963 - CVE-2026-63223-POC (CVE-2026-63223 PoC — CodeIgniter 4 is_image/mime_in File Upload RCE (CVSS 9.8). Unauthenticated remote code execution via unrestricted file upload bypass using image magic bytes. Fixed in v4.7.4.) (August 21, 2026)
- Exploit #12898 - CVE-2026-63223 (CVE-2026-63223 — CI4RCE: CodeIgniter 4 is_image/mime_in File Upload RCE. Magic bytes bypass (getExtension vs getClientExtension). CVSS 9.8 | CWE-434 | CI4 < 4.7.4) (August 14, 2026)