CVE-2021-35301: 
NixOS vulnerability analysis and mitigation

Incorrect Access Control vulnerability in Zammad versions 1.0.x through 4.0.0 allows remote attackers to obtain sensitive information via the Ticket Article detail view. Specifically, the vulnerability could expose agent email addresses to customers instead of showing the email address of the current ticket group (Vendor Advisory).

The vulnerability has been assigned a CVSS v3.1 base score of 5.3 (Medium) with the vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N. The issue stems from improper access control in the ticket article detail view functionality, where the system incorrectly displays agent email addresses to customers in certain circumstances (NVD).

When exploited, this vulnerability allows unauthorized access to sensitive information, specifically exposing email addresses of support agents to customers. This could potentially lead to unwanted direct communication or social engineering attempts targeting support staff (Vendor Advisory).

The vulnerability can be exploited remotely by an attacker without requiring authentication or user interaction. The attack complexity is considered low, making it relatively straightforward to exploit (NVD).

The vulnerability has been fixed in Zammad versions 4.0.1 and 4.1.0. Users are recommended to upgrade to one of these fixed versions. Updates can be obtained through the official Zammad website, FTP server, or via OS package managers (Vendor Advisory).