CVE-2026-56731 in Zammad
Summary
by MITRE • 09/25/2026
Zammad is a web based open source helpdesk/customer support system. Prior to 7.0.1, a low-privilege authenticated user may inject arbitrary HTML markup, including JavaScript event handlers, into a ticket title via the standard ticket creation workflow. The title is persisted without sanitization. This issue is fixed in version 7.0.1.
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Analysis
by VulDB Data Team • 09/25/2026
Zammad serves as a widely deployed open-source helpdesk and customer support platform that facilitates communication between organizations and their customers through web-based interfaces. A significant security vulnerability was identified within versions of Zammad prior to the release of version 7.0.1, specifically affecting the ticket creation workflow. This flaw allows for Cross-Site Scripting attacks by low-privilege authenticated users who have access to create new support tickets. The core technical issue stems from a failure in input validation and output encoding mechanisms when processing user-supplied data destined for display within the application interface.
The specific vulnerability involves the injection of arbitrary HTML markup, including executable JavaScript event handlers, into ticket titles. When an attacker creates a ticket with maliciously crafted content in the title field, the system persists this input without applying adequate sanitization or encoding rules. Consequently, when other users view the ticket details within their web browsers, the browser interprets and executes the injected script code as part of the page's native JavaScript environment. This behavior classifies the vulnerability under CWE-79, which defines Improper Neutralization of Input During Web Page Generation commonly known as Cross-Site Scripting or XSS. The lack of proper context-aware encoding allows scripts to run in the security context of the Zammad application domain rather than being treated as inert data.
The operational impact of this vulnerability is substantial due to its potential for account compromise and session hijacking. An attacker can leverage stored cross-site scripting techniques to steal authentication cookies, session tokens, or other sensitive credentials maintained by the browser for the Zammad instance. By executing arbitrary JavaScript in the context of the victim user's active session, an adversary could perform actions on behalf of that user, such as modifying ticket statuses, accessing confidential customer data, or redirecting users to phishing sites designed to harvest additional credentials. This undermines the integrity and confidentiality guarantees provided by the helpdesk system, potentially exposing sensitive organizational information stored within support tickets.
From a threat modeling perspective aligned with MITRE ATT&CK frameworks, this vulnerability facilitates techniques associated with Collection via Browser Capture of Web Content or Credential Access through Steal Web Session Cookie. The attack vector is classified as low complexity because it requires only authenticated access to the application and does not necessitate complex exploitation chains beyond crafting specific HTTP requests during ticket creation. This makes social engineering tactics highly effective, where an attacker might trick a privileged user into viewing a maliciously crafted ticket title embedded in a shared link or notification email.
Mitigation strategies primarily involve upgrading the Zammad installation to version 7.0.1 or later, which implements robust input sanitization and output encoding practices for all user-controlled fields displayed within the interface. For organizations unable to immediately patch their systems due to operational constraints, temporary mitigations include implementing strict Content Security Policy headers that restrict script execution origins and disable inline scripts where possible. Additionally, deploying a Web Application Firewall with rules capable of detecting and blocking common XSS payloads in HTTP request parameters can provide an additional layer of defense against exploitation attempts while the underlying application code is being updated to address the root cause of the input validation failure.