{"id":"CVE-2026-111056","summary":"FOSSBilling: Unauthenticated client account enumeration via guest signup endpoint","details":"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.","aliases":["GHSA-x4mh-g4pc-wfc5"],"modified":"2026-10-20T02:44:33.777183025Z","published":"2026-10-19T16:00:57.576Z","database_specific":{"cna_assigner":"GitHub_M","cwe_ids":["CWE-200","CWE-204","CWE-307"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/111xxx/CVE-2026-111056.json"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/111xxx/CVE-2026-111056.json"},{"type":"FIX","url":"https://github.com/FOSSBilling/FOSSBilling/commit/19f41ff0a45874c7362b7732c8f68db84bc59c55"},{"type":"FIX","url":"https://github.com/FOSSBilling/FOSSBilling/pull/4234"},{"type":"WEB","url":"https://github.com/FOSSBilling/FOSSBilling/releases/tag/0.8.7"},{"type":"ADVISORY","url":"https://github.com/FOSSBilling/FOSSBilling/security/advisories/GHSA-x4mh-g4pc-wfc5"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-111056"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/fossbilling/fossbilling","events":[{"introduced":"469046158e66d47fa4976703657016961abff3a1"},{"fixed":"29cd19d8793747e86b59a033688e5b9b83de8fab"}],"database_specific":{"extracted_events":[{"introduced":"0.1.0"},{"fixed":"0.8.7"}],"source":"AFFECTED_FIELD"}}],"versions":["0.8.6","0.8.5","0.8.4","0.8.3","0.8.2","0.8.1","0.8.0","0.7.2","0.7.1","0.7.0","0.6.22","0.6.21","0.6.20","0.6.19","0.6.18","0.6.17","0.6.16","0.6.15","0.6.14","0.6.13","0.6.12","0.6.11","0.6.10","0.6.9","0.6.8","0.6.7","0.6.6","0.6.5","0.6.4","0.6.3","0.6.2","0.6.1","0.6.0","0.5.5","0.5.4","0.5.3","0.5.2","0.5.1","0.5.0","0.4.3","0.4.2","0.4.1","0.4.0","0.3.0","0.2.10","0.2.9","0.2.8","0.2.7","0.2.6","0.2.5","0.2.4","0.2.3","0.2.2","0.2.1","0.2.0","0.1.1","0.1.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-111056.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"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"}]}