{"id":"CVE-2026-84465","summary":"Zammad: S/MIME signature verification allows forged sender impersonation","details":"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.","aliases":["GHSA-m9ff-hjr3-93h4"],"modified":"2026-09-27T03:47:33.706592884Z","published":"2026-09-25T18:19:58.735Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/84xxx/CVE-2026-84465.json","cna_assigner":"GitHub_M","cwe_ids":["CWE-290","CWE-295","CWE-347"]},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/84xxx/CVE-2026-84465.json"},{"type":"ADVISORY","url":"https://github.com/zammad/zammad/security/advisories/GHSA-m9ff-hjr3-93h4"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-84465"},{"type":"FIX","url":"https://github.com/zammad/zammad/commit/9a07d0b8214ac4e8e10c23fce71d613bd0625524"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/zammad/zammad","events":[{"introduced":"0"},{"fixed":"9a07d0b8214ac4e8e10c23fce71d613bd0625524"}],"database_specific":{"extracted_events":[{"introduced":"0"},{"fixed":"7.1.2"}],"source":["AFFECTED_FIELD","REFERENCES"]}}],"versions":["7.1.1","7.1.0","7.1.0-alpha","7.0.0-alpha","6.6.0-alpha","6.5.0-alpha","6.4.0-alpha","6.3.0-alpha","6.2.0-alpha","6.1.0-alpha","6.0.0-alpha","5.5.0-alpha","5.4.0-alpha","5.3.0-alpha","5.2.0-alpha","3.7.0","1.6.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-84465.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"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"}]}