CodeIgniter is a PHP full-stack web framework. Prior to CodeIgniter4 version 4.4.3, if an error or exception occurs, a detailed error report is displayed even if in the production environment. As a result, confidential information may be leaked. Version 4.4.3 contains a patch. As a workaround, replace `ini_set('display_errors', '0')` with `ini_set('display_errors', 'Off')` in `app/Config/Boot/production.php`.

CodeIgniter is a PHP full-stack web framework. This vulnerability allows attackers to execute arbitrary code when you use Validation Placeholders. The vulnerability exists in the Validation library, and validation methods in the controller and in-model validation are also vulnerable because they use the Validation library internally. This issue is patched in version 4.3.5.

Shield is an authentication and authorization framework for CodeIgniter 4. This vulnerability may allow [SameSite Attackers](https://canitakeyoursubdomain.name/) to bypass the [CodeIgniter4 CSRF protection](https://codeigniter4.github.io/userguide/libraries/security.html) mechanism with CodeIgniter Shield. For this attack to succeed, the attacker must have direct (or indirect, e.g., XSS) control over a subdomain site (e.g., `https://a.example.com/`) of the target site (e.g., `http://example.com/`). Upgrade to **CodeIgniter v4.2.3 or later** and **Shield v1.0.0-beta.2 or later**. As a workaround: set `Config\Security::$csrfProtection` to `'session,'`remove old session data right after login (immediately after ID and password match) and regenerate CSRF token right after login (immediately after ID and password match)

CodeIgniter through 4.0.0 allows remote attackers to gain privileges via a modified Email ID to the "Select Role of the User" page. NOTE: A contributor to the CodeIgniter framework argues that the issue should not be attributed to CodeIgniter. Furthermore, the blog post reference shows an unknown website built with the CodeIgniter framework but that CodeIgniter is not responsible for introducing this issue because the framework has never provided a login screen, nor any kind of login or user management facilities beyond a Session library. Also, another reporter indicates the issue is with a custom module/plugin to CodeIgniter, not CodeIgniter itself.

EllisLab CodeIgniter 2.1.2 allows remote attackers to bypass the xss_clean() Filter and perform XSS attacks.

A Session Fixation issue exists in CodeIgniter before 3.1.9 because session.use_strict_mode in the Session Library was mishandled.

SQL injection vulnerability in the offset method in the Active Record class in CodeIgniter before 2.2.4 allows remote attackers to execute arbitrary SQL commands via vectors involving the offset variable.

The xss_clean function in CodeIgniter before 2.1.4 might allow remote attackers to bypass an intended protection mechanism and conduct cross-site scripting (XSS) attacks via an unclosed HTML tag.

CodeIgniter before 2.2.0 makes it easier for attackers to decode session cookies by leveraging fallback to a custom XOR-based encryption scheme when the Mcrypt extension for PHP is not available.

CodeIgniter before 3.0 and Kohana 3.2.3 and earlier and 3.3.x through 3.3.2 make it easier for remote attackers to spoof session cookies and consequently conduct PHP object injection attacks by leveraging use of standard string comparison operators to compare cryptographic hashes.

system/libraries/Email.php in CodeIgniter before 3.1.3 allows remote attackers to execute arbitrary code by leveraging control over the email->from field to insert sendmail command-line arguments.