Vulnerability · Published Sep 25, 2026 · Assigned by GitHub_M
CVE-2026-63205Zammad: Channel admins can read unauthorized attachments via signature rich-text body
Medium 5.1
In plain English
A medium-severity authorization bypass via user-controlled key in zammad from zammad. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 25% of all known vulnerabilities).
Official description
Zammad is a web based open source helpdesk/customer support system. Prior to 7.1.2, when creating or updating an email signature, Zammad processes inline images referenced in the signature body. If a signature body contains an HTML img tag pointing to any existing attachment, the system copies that attachment into a new signature-owned record, without checking whether the user has permission to access the original attachment. The newly created copy is then downloadable by the same channel-admin user, because attachment access is determined by the copy's owner (the signature), not the original object (e.g., a ticket or knowledge-base article). This allows a user with any of the admin.channel_email, admin.channel_google, admin.channel_microsoft365, or admin.channel_microsoft_graph permissions to read attachments they would otherwise be denied access to, such as ticket attachments belonging to groups they are not a member of. This issue is fixed in version 7.1.2.
Affected products (as reported)
Weakness: CWE-639, CWE-862 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N