CVE-2021-29487: 
PHP vulnerability analysis and mitigation

OctoberCMS, a CMS platform based on the Laravel PHP Framework, was found to contain an authentication bypass vulnerability (CVE-2021-29487) in the october/system package. The vulnerability was discovered in versions 1.0.471 and 1.1.1, and was patched in versions 1.0.472 and 1.1.5. The issue was disclosed on August 26, 2021 (GitHub Advisory, NVD).

The vulnerability allows an attacker to bypass authentication and take over any user account on an October CMS server through a specially crafted persist cookie. To successfully exploit this vulnerability, the attacker must obtain Laravel's secret key for cookie encryption and signing, and the targeted user account must be logged in during the exploitation. The vulnerability is particularly concerning as authorization attempts via persist cookie are not shown in access logs (GitHub Advisory).

If successfully exploited, this vulnerability allows unauthorized attackers to bypass authentication mechanisms and gain control of any user account on the affected October CMS server. This could lead to unauthorized access to sensitive information, system manipulation, and potential full system compromise (NVD).

The vulnerability has been patched in Build 472 and v1.1.5. For users unable to upgrade, manual application of patches octobercms/library@016a297 and octobercms/library@5bd1a28 is recommended. Additional security recommendations include keeping server OS and system software up to date, using multi-factor authentication plugins, changing the default backend URL or blocking public access to the backend area, and including the Roave/SecurityAdvisories Composer package (GitHub Advisory).