PGP signature spoofing via discarded verification result
Published Sep 25, 2026 · Updated Sep 25, 2026
Improper PGP signature verification in Zammad 7.0.1 and earlier allows remote attackers to present forged inbound email as authentic. The inbound-email handler discards the gpg verification return and always stores a successful signature state with a Good signature label. Exploitation requires PGP integration and a recipient who passively trusts the indicator, allowing altered or fabricated signed content to be accepted as authentic.
Summary
What happened
Improper PGP signature verification in Zammad 7.0.1 and earlier allows remote attackers to present forged inbound email as authentic. The inbound-email handler discards the gpg verification return and always stores a successful signature state with a Good signature label. Exploitation requires PGP integration and a recipient who passively trusts the indicator, allowing altered or fabricated signed content to be accepted as authentic.
The record
- CVE
- CVE-2026-56727
- Published
- Sep 25, 2026
- Updated
- Sep 25, 2026
- Vendor
- Zammad GmbH
- Product
- Zammad
- Classifications
- CWE-391, CWE-347, CWE-287
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Sep 25, 2026CVE publishedPublication date reported by the CVE source.
- Sep 25, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
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- Affected versionversion=< 7.0.2
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Activity data is delayed. The latest report is Sep 28, 2026.
Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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