CVE-2022-40817 in Zammad
Summary
by MITRE • 09/28/2022
Zammad 5.2.1 has a fine-grained permission model that allows to configure read-only access to tickets. However, agents were still wrongly able to perform some operations on such tickets, like adding and removing links, tags. and related answers. This issue has been fixed in 5.2.2.
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Analysis
by VulDB Data Team • 05/22/2025
The vulnerability identified as CVE-2022-40817 affects Zammad version 5.2.1 and represents a critical breakdown in the application's access control mechanisms. This issue manifests within the fine-grained permission model that Zammad implements to manage user access to tickets, specifically targeting the read-only access configuration that should restrict agent interactions with ticket data. The flaw demonstrates a clear privilege escalation vulnerability where users configured with read-only permissions can still perform write operations on ticket objects despite the intended restrictions.
The technical implementation of this vulnerability stems from insufficient validation of user permissions during ticket manipulation operations. When agents attempt to add or remove links, tags, and related answers to tickets, the system fails to properly verify whether the user possesses the necessary write permissions. This permission bypass occurs at the application logic level where the access control checks are either missing or improperly implemented, allowing unauthorized modifications to persist even when read-only access is explicitly configured. The vulnerability is particularly concerning because it operates at the core of Zammad's ticket management functionality, undermining the fundamental security principle of least privilege.
The operational impact of this vulnerability extends beyond simple data integrity concerns to potentially compromise the entire ticket management workflow and audit trail. Agents with read-only access could manipulate ticket relationships, alter tag assignments, and modify answer content, which would create inconsistencies in ticket history and potentially obscure important investigative information. This issue directly violates the principle of information classification and access control as defined in the CWE-284 access control weakness category, where improper access control allows users to perform actions beyond their assigned permissions. The vulnerability could enable malicious actors with read-only access to escalate their privileges and manipulate ticket data to influence investigations or hide evidence of their activities.
This vulnerability aligns with several ATT&CK framework techniques including privilege escalation through access control weaknesses and defense evasion by manipulating audit trails. The flaw represents a failure in the application's authorization controls, specifically targeting the T1078 technique related to valid accounts and T1566 related to credential access through unauthorized access. Organizations using Zammad for customer support, incident response, or help desk operations face significant risks from this vulnerability, as it could enable unauthorized modifications to critical support tickets that may contain sensitive customer information or security incident details.
The remediation for this vulnerability requires immediate deployment of Zammad version 5.2.2, which includes the necessary patches to fix the permission validation logic. System administrators should conduct comprehensive audits of existing permission configurations to identify any potential misuse of read-only access that may have occurred prior to the patch deployment. Additionally, organizations should implement monitoring solutions that track ticket modification activities, particularly for users configured with read-only access, to detect any unauthorized activities that may have bypassed the permission controls. The fix addresses the underlying access control implementation by ensuring proper permission validation occurs before any ticket modification operations are permitted, thereby restoring the intended security boundaries within the application's permission model and preventing unauthorized write operations on tickets.