An issue was discovered in Zammad before 6.2.0. When listing tickets linked to a knowledge base answer, or knowledge base answers of a ticket, a user could see entries for which they lack permissions.

An issue was discovered in Zammad before 6.2.0. An attacker can trigger phishing links in generated notification emails via a crafted first or last name.

An issue was discovered in Zammad before 6.2.0. Due to lack of rate limiting in the "email address verification" feature, an attacker could send many requests for a known address to cause Denial Of Service (generation of many emails, which would also spam the victim).

An issue was discovered in Zammad before 6.2.0. In several subsystems, SSL/TLS was used to establish connections to external services without proper validation of hostname and certificate authority. This is exploitable by man-in-the-middle attackers.

An issue was discovered in Zammad before 6.2.0. It uses the public endpoint /api/v1/signshow for its login screen. This endpoint returns internal configuration data of user object attributes, such as selectable values, which should not be visible to the public.

An issue in Zammad v5.4.0 allows attackers to bypass e-mail verification using an arbitrary address and manipulate the data of the generated user. Attackers are also able to gain unauthorized access to existing tickets.

Zammad 5.3.x (Fixed in 5.4.0) is vulnerable to Incorrect Access Control. An authenticated attacker with agent and customer roles could perform unauthorized changes on articles where they only have customer permissions.

Zammad 5.3.x (Fixed 5.4.0) is vulnerable to Incorrect Access Control. An authenticated attacker could gain information about linked accounts of users involved in their tickets using the Zammad API.

Insufficient privilege verification in Zammad v5.3.0 allows an authenticated attacker to perform changes on the tags of their customer tickets using the Zammad API. This is now corrected in v5.3.1 so that only agents with write permissions may change ticket tags.

An issue in the component /api/v1/mentions of Zammad v5.3.0 allows authenticated attackers with agent permissions to view information about tickets they are not authorized to see.