{"id":"CVE-2026-111056","state":"PUBLISHED","title":"FOSSBilling: Unauthenticated client account enumeration via guest signup endpoint","description":"FOSSBilling is an open source billing and client-management platform. From 0.1.0 until 0.8.7, the unauthenticated POST /api/guest/client/create endpoint reveals whether a submitted email belongs to a registered client because guest signup returns a distinct unredacted error when the submitted email already exists. The trigger is an unauthenticated request to POST /api/guest/client/create with a target email address. An attacker can compare the guest-signup response for a target email to determine whether the email belongs to an existing FOSSBilling client. Box\\Mod\\Client\\Api\\Guest::create returns the error after Client\\Service::clientAlreadyExists finds a matching record, and the API response exposes that exception message without redaction. This issue is fixed in version 0.8.7.","publishedAt":"2026-10-19T16:00:57.576Z","updatedAt":"2026-10-22T03:02:43.261Z","severity":{"score":6.9,"label":"Medium","version":"4.0","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["FOSSBilling FOSSBilling"],"affected":[{"vendor":"FOSSBilling","product":"FOSSBilling","versions":[{"version":">= 0.1.0, < 0.8.7","status":"affected"}]}],"references":["https://github.com/FOSSBilling/FOSSBilling/security/advisories/GHSA-x4mh-g4pc-wfc5","https://github.com/FOSSBilling/FOSSBilling/pull/4234","https://github.com/FOSSBilling/FOSSBilling/commit/19f41ff0a45874c7362b7732c8f68db84bc59c55","https://github.com/FOSSBilling/FOSSBilling/releases/tag/0.8.7"],"weaknesses":["CWE-200","CWE-204","CWE-307"],"ingestedAt":"2026-10-29T20:10:33.477Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/111xxx/CVE-2026-111056.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-111056","state":"PUBLISHED","datePublished":"2026-10-19T16:00:57.576Z","dateUpdated":"2026-10-22T03:02:43.261Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-10-15T12:47:13.664Z"},"containers":{"cna":{"title":"FOSSBilling: Unauthenticated client account enumeration via guest signup endpoint","descriptions":[{"lang":"en","value":"FOSSBilling is an open source billing and client-management platform. From 0.1.0 until 0.8.7, the unauthenticated POST /api/guest/client/create endpoint reveals whether a submitted email belongs to a registered client because guest signup returns a distinct unredacted error when the submitted email already exists. The trigger is an unauthenticated request to POST /api/guest/client/create with a target email address. An attacker can compare the guest-signup response for a target email to determine whether the email belongs to an existing FOSSBilling client. Box\\Mod\\Client\\Api\\Guest::create returns the error after Client\\Service::clientAlreadyExists finds a matching record, and the API response exposes that exception message without redaction. This issue is fixed in version 0.8.7."}],"affected":[{"vendor":"FOSSBilling","product":"FOSSBilling","versions":[{"version":">= 0.1.0, < 0.8.7","status":"affected"}]}],"references":[{"url":"https://github.com/FOSSBilling/FOSSBilling/security/advisories/GHSA-x4mh-g4pc-wfc5","name":"https://github.com/FOSSBilling/FOSSBilling/security/advisories/GHSA-x4mh-g4pc-wfc5","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/FOSSBilling/FOSSBilling/pull/4234","name":"https://github.com/FOSSBilling/FOSSBilling/pull/4234","tags":["x_refsource_MISC"]},{"url":"https://github.com/FOSSBilling/FOSSBilling/commit/19f41ff0a45874c7362b7732c8f68db84bc59c55","name":"https://github.com/FOSSBilling/FOSSBilling/commit/19f41ff0a45874c7362b7732c8f68db84bc59c55","tags":["x_refsource_MISC"]},{"url":"https://github.com/FOSSBilling/FOSSBilling/releases/tag/0.8.7","name":"https://github.com/FOSSBilling/FOSSBilling/releases/tag/0.8.7","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV4_0":{"attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"NONE","privilegesRequired":"NONE","userInteraction":"NONE","vulnConfidentialityImpact":"LOW","vulnIntegrityImpact":"NONE","vulnAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","subAvailabilityImpact":"NONE","baseScore":6.9,"baseSeverity":"MEDIUM","vectorString":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N","version":"4.0"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-200","lang":"en","description":"CWE-200: Exposure of Sensitive Information to an Unauthorized Actor","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-204","lang":"en","description":"CWE-204: Observable Response Discrepancy","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-307","lang":"en","description":"CWE-307: Improper Restriction of Excessive Authentication Attempts","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-10-19T16:00:57.576Z"},"source":{"advisory":"GHSA-x4mh-g4pc-wfc5","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-10-22T03:02:31.174115Z","id":"CVE-2026-111056","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-22T03:02:43.261Z"}}]}}}