CVE-2023-43336: Privilege Escalation Vulnerability in FreePBX

CVE-2023-43336: Privilege Escalation Vulnerability in FreePBX

FreePBX is a popular open-source web-based graphical user interface that manages Asterisk, a communication server. FreePBX allows users to configure and manage their communication systems easily. However, a security vulnerability was discovered in FreePBX version 16.0.26 that could potentially lead to privilege escalation, enabling unauthorized users to access sensitive information and compromise system integrity. 

About the CVE

CVE-2023-43336 is a high-level privilege escalation vulnerability identified in FreePBX version 16.0.26. It allows least privilege users to access information belonging to other users, violating access controls and potentially leading to authorized data disclosure and system compromise.  

What’s the cause of this vulnerability?

The cause of this vulnerability arose due to the improper access controls and untrusted input handling in the application’s codebase. 


In August 2023, our team discovered the CVE-2023-43336 vulnerability in FreePBX version 16.0.26. They uncovered this vulnerability through careful analysis and testing which allowed them to apply series of steps to bypass controls and access sensitive data, such as call history, belonging to other users.    

What we found

Our team identified “Privilege Escalation” Vulnerability where the main motive of the attacker is to gain high-level unauthorized access within a security system The attacker typically starts with exploiting vulnerabilities to access a system that has limited privileges 

Brief about what we found

Our team discovered the vulnerability by analysing the behaviour of the application. By logging in with a non-administrative user account with access to the “Call History” modules, they were able to trigger requests and observe the data exchange.  

Through a series of steps, including adding a specific widget to the dashboard and manipulating requests, our team successfully accessed call history data belonging to other users, circumventing the access restrictions implemented by the application.

We helped them mitigate the following risks

Privilege Escalation Vulnerability:

A Privilege Escalation vulnerability is a vulnerability that allows an attacker to gain higher levels of access or permissions within a system or application than they are authorized to have. This type of vulnerability typically arises due to inadequate access controls or flawed permission management within the software. Once exploited, privilege vulnerabilities can enable attackers to execute malicious actions, access sensitive data, and compromise the security of the system or application.

Business risks we prevented:

  1. Breaches of user privacy.
  2. Unauthorised access to sensitive information.
  3. Data theft.
  4. System integrity.
  5. Reputational damage.
  6. Financial loss.


The privilege escalation vulnerability discovered in FreePBX version 16.0.26 underscored the critical importance of robust security practices in software development. The timely identification and remediation of this vulnerability highlighted the importance of proactive security practices in mitigating risks to sensitive data and system integrity. This case highlighted the ongoing need for proactive security measures, including vulnerability assessments, timely patching, and user education, to defend against the evolving cybersecurity threats and ensure the resilience of communication infrastructure.


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