CVE-2026-63206 Details
Description
Zammad is a web based open source helpdesk/customer support system. Prior to 7.1.2, zammad's HTML sanitizer, which blocks remote images in ticket articles and email views, can be bypassed using a shortened URL format that omits the double slash after the scheme (for example a shortened HTTP URL instead of a shortened HTTP URL). Modern browsers treat both forms as equivalent remote URLs. As a result, an attacker who sends a crafted email or ticket can cause the recipient's browser to silently load an image from an external server, revealing when and by whom the ticket was opened. Zammad's "remote content blocked" warning is not shown because the sanitizer does not recognize the shortened form as remote. This issue is fixed in version 7.1.2.
A vulnerability in Zammad's HTML sanitizer prior to version 7.1.2 allows for remote image tracking bypass in ticket articles and email views. The sanitizer, which is supposed to block remote images, can be circumvented using a shortened URL format that omits the double slash after the scheme. Modern browsers treat both forms as equivalent remote URLs. This flaw enables an attacker to send a crafted email or ticket that silently loads an image from an external server, thereby revealing when and by whom the ticket was opened. The issue arises because the sanitizer does not recognize the shortened URL as remote, and as a result, Zammad's 'remote content blocked' warning is not displayed.
Users can upgrade to Zammad version 7.1.2 or later to address this vulnerability.
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed Sep 25, 2026CISA-ADP
Assessed Sep 25, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/zammad/zammad/commit/a5878f37e4010f0b3bec85dae35af964cc1c8019 | [email protected] | Source CodeVendor |
| https://github.com/zammad/zammad/security/advisories/GHSA-fpwp-w2p4-hqg7 | [email protected] | AdvisoryRemedyVendor |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-184 | Incomplete List of Disallowed Inputs | [email protected] |
| CWE-20 | Improper Input Validation | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| Zammad | <= 7.1.1 (semver) |
CPE
Remediation
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Change History
2 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Sep 25, 2026 | CVE Modified | CISA-ADP |
| Sep 25, 2026 | New CVE Received | [email protected] |