{"id":"CVE-2026-55187","state":"PUBLISHED","title":"Mailpit: Incomplete SSRF protection in Link Check API via IPv6 transition mechanisms (follow-up to CVE-2026-27808)","description":"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.","publishedAt":"2026-07-10T21:43:59.548Z","updatedAt":"2026-07-13T15:55:15.065Z","severity":{"score":5.8,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["axllent mailpit"],"affected":[{"vendor":"axllent","product":"mailpit","versions":[{"version":"< 1.30.2","status":"affected"}]}],"references":["https://github.com/axllent/mailpit/security/advisories/GHSA-w4mc-hhc6-xp28","https://github.com/axllent/mailpit/commit/a88dadbbe1df016a35a445089ef2a362a6c2de78","https://github.com/axllent/mailpit/releases/tag/v1.30.2"],"weaknesses":["CWE-918"],"ingestedAt":"2026-10-29T20:12:24.861Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/55xxx/CVE-2026-55187.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-55187","state":"PUBLISHED","datePublished":"2026-07-10T21:43:59.548Z","dateUpdated":"2026-07-13T15:55:15.065Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-06-16T15:20:43.086Z"},"containers":{"cna":{"title":"Mailpit: Incomplete SSRF protection in Link Check API via IPv6 transition mechanisms (follow-up to CVE-2026-27808)","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"axllent","product":"mailpit","versions":[{"version":"< 1.30.2","status":"affected"}]}],"references":[{"url":"https://github.com/axllent/mailpit/security/advisories/GHSA-w4mc-hhc6-xp28","name":"https://github.com/axllent/mailpit/security/advisories/GHSA-w4mc-hhc6-xp28","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/axllent/mailpit/commit/a88dadbbe1df016a35a445089ef2a362a6c2de78","name":"https://github.com/axllent/mailpit/commit/a88dadbbe1df016a35a445089ef2a362a6c2de78","tags":["x_refsource_MISC"]},{"url":"https://github.com/axllent/mailpit/releases/tag/v1.30.2","name":"https://github.com/axllent/mailpit/releases/tag/v1.30.2","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":5.8,"baseSeverity":"MEDIUM","confidentialityImpact":"LOW","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"CHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-918","lang":"en","description":"CWE-918: Server-Side Request Forgery (SSRF)","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-07-10T21:43:59.548Z"},"source":{"advisory":"GHSA-w4mc-hhc6-xp28","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://github.com/axllent/mailpit/security/advisories/GHSA-w4mc-hhc6-xp28","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-07-13T15:55:02.724130Z","id":"CVE-2026-55187","options":[{"Exploitation":"poc"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-07-13T15:55:15.065Z"}}]}}}