CVE-2026-55187 (GCVE-0-2026-55187)

Vulnerability from cvelistv5 – Published: 2026-07-10 21:43 – Updated: 2026-07-10 21:43
VLAI
Title
Mailpit: Incomplete SSRF protection in Link Check API via IPv6 transition mechanisms (follow-up to CVE-2026-27808)
Summary
Mailpit is an email testing tool and API for developers. Prior to 1.30.2, the remediation shipped for CVE-2026-27808 is incomplete because the tools.IsInternalIP deny-list in internal/tools/net.go relies on Go's standard library classification helpers and does not block IPv6 transition mechanisms or prefixes such as NAT64, 6to4, IPv4-compatible IPv6, ISATAP, fec0::/10, and 2001:db8::/32. An attacker who can deliver email and invoke POST /api/v1/message/{ID}/link-check can coerce the Link Check API's safeDialContext path into dialing internal destinations and can use status-code and error feedback to map internal service reachability, including cloud metadata endpoints. This issue is fixed in version 1.30.2.
Severity
5.8 (Medium)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N
CWE
  • CWE-918 - Server-Side Request Forgery (SSRF)
Assigner
References
Impacted products
Vendor Product Version
axllent mailpit Affected: < 1.30.2
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{
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          "vendor": "axllent",
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        }
      ],
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            "baseScore": 5.8,
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            "scope": "CHANGED",
            "userInteraction": "NONE",
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            "version": "3.1"
          }
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      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-918",
              "description": "CWE-918: Server-Side Request Forgery (SSRF)",
              "lang": "en",
              "type": "CWE"
            }
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      "providerMetadata": {
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      },
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        }
      ],
      "source": {
        "advisory": "GHSA-w4mc-hhc6-xp28",
        "discovery": "UNKNOWN"
      },
      "title": "Mailpit: Incomplete SSRF protection in Link Check API via IPv6 transition mechanisms (follow-up to CVE-2026-27808)"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-55187",
    "datePublished": "2026-07-10T21:43:59.548Z",
    "dateReserved": "2026-06-16T15:20:43.086Z",
    "dateUpdated": "2026-07-10T21:43:59.548Z",
    "state": "PUBLISHED"
  },
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  "dataVersion": "5.2",
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  }
}



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