EXECUTIVE SUMMARY:
CVE-2026-48062 with a CVSS score of 9.8 is a critical vulnerability in the CodeIgniter4 framework where the ext_in upload validation rule fails to properly check the client-provided filename extension, instead relying on the MIME-derived guessed extension. This allows an attacker to bypass validation by uploading a malicious file, such as a PHP shell, with a disguised extension, for example, naming a PHP file as shell php but with GIF-like content, which would pass validation as a GIF file due to its detected MIME type. An attacker can exploit this vulnerability by uploading a malicious file to a vulnerable application that accepts user-controlled uploads, relies on the ext_in rule for validation, and stores uploaded files in a web-accessible directory, requiring access to the upload endpoint and the ability to save files with executable extensions, ultimately gaining the capability to execute arbitrary code on the server. The business impact of this vulnerability is significant, as it can lead to a complete compromise of the application and its data, with consequences including data breaches, lateral movement, and further attacks. Prerequisites for exploitation include the application accepting user-controlled uploads, relying on the vulnerable validation rule, and storing uploads in a web-accessible directory where executable files can run.[/subscribe_to_unlock_form]
EXECUTIVE SUMMARY:
CVE-2026-48062 with a CVSS score of 9.8 is a critical vulnerability in the CodeIgniter4 framework where the ext_in upload validation rule fails to properly check the client-provided filename extension, instead relying on the MIME-derived guessed extension. This allows an attacker to bypass validation by uploading a malicious file, such as a PHP shell, with a disguised extension, for example, naming a PHP file as shell php but with GIF-like content, which would pass validation as a GIF file due to its detected MIME type. An attacker can exploit this vulnerability by uploading a malicious file to a vulnerable application that accepts user-controlled uploads, relies on the ext_in rule for validation, and stores uploaded files in a web-accessible directory, requiring access to the upload endpoint and the ability to save files with executable extensions, ultimately gaining the capability to execute arbitrary code on the server. The business impact of this vulnerability is significant, as it can lead to a complete compromise of the application and its data, with consequences including data breaches, lateral movement, and further attacks. Prerequisites for exploitation include the application accepting user-controlled uploads, relying on the vulnerable validation rule, and storing uploads in a web-accessible directory where executable files can run.[emaillocker id="1283"]
RECOMMENDATION:
REFERENCES:
The following reports contain further technical details:
https://github.com/advisories/GHSA-2gr4-ppc7-7mhx
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