CVE-2026-84465Zammad: S/MIME signature verification allows forged sender impersonation
Updated under an hour ago ()
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No exploitation reported and no EPSS estimate yet.
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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.
- CVSS
- 7.1 HIGH (v4.0, CNA)CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
- Weakness (CWE)
- CWE-290, CWE-295, CWE-347
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- GitHub_M
- NVD analysis
- Deferred
- Record last updated
- Sep 29, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
zammad zammad zammad:zammad (from the name) | before 7.1.2 | CNA record |
References
- https://github.com/zammad/zammad/security/advisories/GHSA-m9ff-hjr3-93h4x-refsource-confirm
- https://github.com/zammad/zammad/commit/9a07d0b8214ac4e8e10c23fce71d613bd0625524x-refsource-misc
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.