CVE-2026-84465 (GCVE-0-2026-84465)

Vulnerability from cvelistv5 – Published: 2026-09-25 18:19 – Updated: 2026-09-25 18:19
VLAI
Title
Zammad: S/MIME signature verification allows forged sender impersonation
Summary
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.
Severity
7.1 (High)
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
CWE
  • CWE-290 - Authentication Bypass by Spoofing
  • CWE-295 - Improper Certificate Validation
  • CWE-347 - Improper Verification of Cryptographic Signature
Assigner
References
Impacted products
Vendor Product Version CPE status
zammad zammad Affected: < 7.1.2
guessed Create a notification for this product.
Show details on NVD website
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        }
      ],
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            "privilegesRequired": "NONE",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "PASSIVE",
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              "type": "CWE"
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        },
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            }
          ]
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        {
          "descriptions": [
            {
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              "description": "CWE-347: Improper Verification of Cryptographic Signature",
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      "providerMetadata": {
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        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
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          "tags": [
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          "url": "https://github.com/zammad/zammad/security/advisories/GHSA-m9ff-hjr3-93h4"
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          "tags": [
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          "url": "https://github.com/zammad/zammad/commit/9a07d0b8214ac4e8e10c23fce71d613bd0625524"
        }
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      "source": {
        "advisory": "GHSA-m9ff-hjr3-93h4",
        "discovery": "UNKNOWN"
      },
      "title": "Zammad: S/MIME signature verification allows forged sender impersonation"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
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    "cveId": "CVE-2026-84465",
    "datePublished": "2026-09-25T18:19:58.735Z",
    "dateReserved": "2026-09-01T20:05:09.424Z",
    "dateUpdated": "2026-09-25T18:19:58.735Z",
    "state": "PUBLISHED"
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    "nvd": {
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          }
        ],
        "id": "CVE-2026-84465",
        "lastModified": "2026-09-28T14:45:39.697",
        "metrics": {
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                "exploitMaturity": "NOT_DEFINED",
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                "modifiedAttackComplexity": "NOT_DEFINED",
                "modifiedAttackRequirements": "NOT_DEFINED",
                "modifiedAttackVector": "NOT_DEFINED",
                "modifiedPrivilegesRequired": "NOT_DEFINED",
                "modifiedSubAvailabilityImpact": "NOT_DEFINED",
                "modifiedSubConfidentialityImpact": "NOT_DEFINED",
                "modifiedSubIntegrityImpact": "NOT_DEFINED",
                "modifiedUserInteraction": "NOT_DEFINED",
                "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
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                "modifiedVulnIntegrityImpact": "NOT_DEFINED",
                "privilegesRequired": "NONE",
                "providerUrgency": "NOT_DEFINED",
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                "subConfidentialityImpact": "NONE",
                "subIntegrityImpact": "NONE",
                "userInteraction": "PASSIVE",
                "valueDensity": "NOT_DEFINED",
                "vectorString": "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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
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                "vulnerabilityResponseEffort": "NOT_DEFINED"
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    }
  }
}



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