CVE-2021-33816: 
PHP vulnerability analysis and mitigation

CVE-2021-33816 is a critical vulnerability discovered in Dolibarr ERP & CRM version 13.0.2, specifically affecting its website builder module. The vulnerability was discovered on June 1, 2021, and publicly disclosed on November 10, 2021. This security flaw allows for authenticated remote code execution due to incomplete protection mechanisms in the application (Trovent Advisory).

The vulnerability stems from an incomplete protection mechanism in the website builder module where system, exec, and shellexec functions are blocked, but backticks are not. This oversight allows attackers to execute arbitrary PHP code using backtick operators, which function similarly to shellexec(). The vulnerability has been assigned a CVSS v3.1 score of 9.1 (Critical) with the vector string CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H and is classified under CWE-94 (Trovent Advisory, NVD).

The vulnerability allows authenticated attackers to execute arbitrary system commands on the affected server, potentially leading to complete system compromise. This could result in unauthorized access to sensitive data, system modification, and potential service disruption (Trovent Advisory).

The vulnerability was fixed in Dolibarr version 14.0.0. For systems unable to update immediately, it is recommended to disable the 'websites' module until the fixed version can be deployed (Trovent Advisory).