CVE-2026-63205

Beschreibung

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.

Erkennung & Indikatoren

DeviceProcessEvents
| where InitiatingProcessCommandLine contains "img tag" and InitiatingProcessCommandLine contains "/api/v1/attachments/"
| where InitiatingProcessParentFileName == "zammad" or FileName == "zammad"

(sourcetype=zammad OR source=zammad) "img tag" "/api/v1/attachments/"

title: Zammad Unauthorized Attachment Access
id: 00000000-0000-0000-0000-000000000000
status: experimental
description: Detects attempts to access unauthorized attachments in Zammad via email signature processing.
author: SecBoard
date: 2024/01/01
logsource:
  product: zammad
  service: application
detection:
  selection:
    - message|contains: 'img tag'
    - message|contains: '/api/v1/attachments/'
  condition: selection
level: medium

from logs-zammad.*
| where message : "img tag" and message : "/api/v1/attachments/"
| sort @timestamp desc

Referenzen

• https://github.com/zammad/zammad/commit/f3e4da83621efad8443a4e9fe6bd87befad47c44
• https://github.com/zammad/zammad/security/advisories/GHSA-pp8r-x7pp-5qj5