# CVE-2026-63206: Zammad HTML sanitizer bypass via shortened URL scheme

Source: https://junglewise.ai/threats/cve-2026-63206-zammad-is-a-web-based-open-source-helpdesk-customer-support  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-25. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-63206 · Severity: info · Published 2026-09-25

Zammad is an open-source helpdesk and customer support system that sanitizes HTML to block remote images for privacy. An attacker can bypass this protection by using a shortened URL format (e.g., http:example.com/pixel instead of http://example.com/pixel) that modern browsers still interpret as remote URLs. This allows an attacker to load invisible tracking images when a support agent opens a crafted ticket or email, revealing who accessed the ticket and when without triggering the normal "remote content blocked" warning.

Technologies: [Zammad](https://junglewise.ai/threats/technologies/zammad). Vendors: [Zammad](https://junglewise.ai/threats/vendors/zammad).

## Quick answers

**Is CVE-2026-63206 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-63206 being exploited in the wild.

**How severe is CVE-2026-63206?** Informational severity, published 25 September 2026.

**Which products and versions are affected?** Zammad 7.1.1 and earlier.

**Is there a fix for CVE-2026-63206?** A patch was published on 2026-09-25: Fixed in version 7.1.2 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-63206 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-63206?** Check whether you run Zammad at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The vulnerability is an HTML sanitizer bypass in the remote URL detection logic that fails to recognize shortened URL schemes (single slash instead of double slash after the protocol). An unauthenticated attacker can inject crafted HTML with these malformed URLs into ticket articles or emails, and when a user views the content, their browser silently loads a remote image from an attacker-controlled server, disclosing access patterns. The fix in version 7.1.2 improves the URL schema checking to reject both standard and shortened formats.

## Affected products

- Zammad Zammad 7.1.1 and earlier

## Timeline

- 2026-08-04: disclosed
- 2026-09-25: patched: Fixed in version 7.1.2

## References

- [https://github.com/zammad/zammad/commit/a5878f37e4010f0b3bec85dae35af964cc1c8019](https://github.com/zammad/zammad/commit/a5878f37e4010f0b3bec85dae35af964cc1c8019)
- [https://github.com/zammad/zammad/security/advisories/GHSA-fpwp-w2p4-hqg7](https://github.com/zammad/zammad/security/advisories/GHSA-fpwp-w2p4-hqg7)

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