Zammad up to 7.1.1 S/MIME certificate validation

Summaryinfo

A vulnerability marked as problematic has been reported in Zammad up to 7.1.1. Affected by this vulnerability is an unknown functionality of the component S/MIME. Performing a manipulation results in certificate validation. This vulnerability is identified as CVE-2026-84465. The attack can be initiated remotely. There is not any exploit available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as problematic, was found in Zammad up to 7.1.1. This affects an unknown code of the component S/MIME. The manipulation with an unknown input leads to a certificate validation vulnerability. CWE is classifying the issue as CWE-295. The product does not validate, or incorrectly validates, a certificate. This is going to have an impact on integrity. The summary by CVE is:

Zammad is a web based open source helpdesk/customer support system. Prior to 7.1.2, when Zammad checks the digital signature on an incoming S/MIME-signed email, it does not verify that the signing certificate is genuinely trusted, it only checks whether a certificate with a matching name is already stored in the system. An attacker can create their own certificate using the name of a real, previously trusted sender and use it to send a forged email. Zammad will display that email with the same "validly signed" indicator as a genuine message from the real sender, even though the attacker never had access to that sender's actual certificate or private key. This issue is fixed in version 7.1.2.

The advisory is shared at github.com. This vulnerability is uniquely identified as CVE-2026-84465 since 09/01/2026. The exploitability is told to be difficult. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. Neither technical details nor an exploit are publicly available. MITRE ATT&CK project uses the attack technique T1587.003 for this issue.

Upgrading to version 7.1.2 eliminates this vulnerability.

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Productinfo

Name

• Zammad

Version

• 7.1.0
• 7.1.1

License

• open-source

Website

• Product: https://github.com/zammad/zammad/

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