# CVE-2026-84458: Zammad account takeover via unverified email matching in SSO auto-link

Source: https://junglewise.ai/threats/cve-2026-84458-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-2026-84458 · Severity: info · Published 2026-09-25

Zammad is a web-based helpdesk and customer support system. When the "Automatic account link on initial logon" SSO feature is enabled, attackers can take over any user account—including administrators—by setting an email address in their identity provider to match a victim's account. This completely bypasses the victim's password and grants full access to their account and all its privileges.

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

## Quick answers

**Is CVE-2026-84458 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-84458 being exploited in the wild.

**How severe is CVE-2026-84458?** Informational severity, published 25 September 2026.

**Which products and versions are affected?** Zammad prior to 7.1.2.

**Is there a fix for CVE-2026-84458?** A patch was published on 2026-09-25: Version 7.1.2 released Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-84458 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-84458?** 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 exists in the automatic SSO account linking logic, which matches incoming identities to local accounts based on email address alone without verifying that the identity provider confirmed ownership of that email. An attacker controlling any identity at a configured provider (including any Azure AD tenant via the default multi-tenant Microsoft 365 /common app registration) can exploit this by setting their identity's email to a victim's address, authenticating, and gaining full access as that user. The fix in version 7.1.2 adds email ownership verification and honors the xms_edov ID token claim.

## Affected products

- Zammad Zammad prior to 7.1.2

## Timeline

- 2026-08-04: disclosed
- 2026-09-25: patched: Version 7.1.2 released

## References

- [https://github.com/zammad/zammad/commit/0dba387df8e2b46956907975034cd44e4d021b1c](https://github.com/zammad/zammad/commit/0dba387df8e2b46956907975034cd44e4d021b1c)
- [https://github.com/zammad/zammad/security/advisories/GHSA-86cc-3ggh-mf2m](https://github.com/zammad/zammad/security/advisories/GHSA-86cc-3ggh-mf2m)

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