Arbitrary file upload in CodeIgniter4 - #VU155854
Published: October 15, 2026
Vulnerability identifier: #VU155854
CSH Severity: Medium
CVSS v4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N]
CVE-ID: N/A
CWE-ID: CWE-434
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to bypass file upload type, extension, size, and dimension restrictions.
The vulnerability exists due to premature validation success in CodeIgniterValidationFileRules and CodeIgniterValidationStrictRulesFileRules when processing a multiple-file upload containing an empty file entry. A remote attacker can submit an entry with UPLOAD_ERR_NO_FILE before a disallowed file to bypass file upload type, extension, size, and dimension restrictions.
Exploitation requires an application that validates an optional multiple-file field without the uploaded[field] rule and then saves the remaining files while skipping empty entries.
Affected software
CodeIgniter4
Remediation
Install security update from vendor's website.
CodeIgniter4 - update to 4.7.5