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CVE-2026-56728: Zammad: Cross-User Taskbar Item Access Control Vulnerability

• Severity: medium (CVSS 5.3 v4.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-25 · updated 2026-09-28
• Weakness: CWE-200

Description

Zammad is a web based open source helpdesk/customer support system. Prior to 7.0.2, a broken access control vulnerability exists in Zammad's GraphQL API. An authenticated user can access taskbar item data belonging to another user by crafting a request with the target user's taskbar identifier. The taskbar feature stores transient state for active user sessions, including auto-saved ticket drafts. Under certain conditions, the authorization check for taskbar item access is not enforced, allowing a user to read another user's taskbar item data. This vulnerability is fixed in 7.0.2.

Affected products

• zammad: before 7.0.2

References

• https://github.com/zammad/zammad/commit/4ccd5d573023b66b0d0184914c92417e1780793f
• https://github.com/zammad/zammad/releases/tag/7.0.2
• https://github.com/zammad/zammad/security/advisories/GHSA-jvcg-5539-vvc3

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