{"id":"CVE-2026-33543","state":"PUBLISHED","title":"FOSSBilling: Authentication bypass allows unauthenticated administrator creation","description":"FOSSBilling is a free, open-source billing and client management system. Versions 0.7.2 and prior expose a guest API endpoint, /api/guest/staff/create, intended for initial administrator bootstrap. Due to a flawed admin-existence check, the endpoint remains usable after an administrator already exists. The flawed guard check uses is_countable() on a value that returns a Model_Admin object or null rather than a countable type, causing the expression to always evaluate as true and bypass the intended protection. As a result, an attacker can reach the unprotected endpoint to create a new administrator account and immediately authenticate, gaining a fully privileged admin session even when an admin already exists. This issue has been fixed in version 0.8.0.","publishedAt":"2026-06-24T21:01:16.544Z","updatedAt":"2026-06-25T13:22:14.263Z","severity":{"score":9.3,"label":"Critical","version":"4.0","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["FOSSBilling FOSSBilling"],"affected":[{"vendor":"FOSSBilling","product":"FOSSBilling","versions":[{"version":"< 0.8.0","status":"affected"}]}],"references":["https://github.com/FOSSBilling/FOSSBilling/security/advisories/GHSA-28mh-j262-q49w","https://github.com/FOSSBilling/FOSSBilling/releases/tag/0.8.0"],"weaknesses":["CWE-288","CWE-306"],"ingestedAt":"2026-10-29T20:11:40.391Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/33xxx/CVE-2026-33543.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-33543","state":"PUBLISHED","datePublished":"2026-06-24T21:01:16.544Z","dateUpdated":"2026-06-25T13:22:14.263Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-03-20T18:05:11.832Z"},"containers":{"cna":{"title":"FOSSBilling: Authentication bypass allows unauthenticated administrator creation","descriptions":[{"lang":"en","value":"FOSSBilling is a free, open-source billing and client management system. Versions 0.7.2 and prior expose a guest API endpoint, /api/guest/staff/create, intended for initial administrator bootstrap. Due to a flawed admin-existence check, the endpoint remains usable after an administrator already exists. The flawed guard check uses is_countable() on a value that returns a Model_Admin object or null rather than a countable type, causing the expression to always evaluate as true and bypass the intended protection. As a result, an attacker can reach the unprotected endpoint to create a new administrator account and immediately authenticate, gaining a fully privileged admin session even when an admin already exists. This issue has been fixed in version 0.8.0."}],"affected":[{"vendor":"FOSSBilling","product":"FOSSBilling","versions":[{"version":"< 0.8.0","status":"affected"}]}],"references":[{"url":"https://github.com/FOSSBilling/FOSSBilling/security/advisories/GHSA-28mh-j262-q49w","name":"https://github.com/FOSSBilling/FOSSBilling/security/advisories/GHSA-28mh-j262-q49w","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/FOSSBilling/FOSSBilling/releases/tag/0.8.0","name":"https://github.com/FOSSBilling/FOSSBilling/releases/tag/0.8.0","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV4_0":{"attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"NONE","privilegesRequired":"NONE","userInteraction":"NONE","vulnConfidentialityImpact":"HIGH","vulnIntegrityImpact":"HIGH","vulnAvailabilityImpact":"HIGH","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","subAvailabilityImpact":"NONE","baseScore":9.3,"baseSeverity":"CRITICAL","vectorString":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N","version":"4.0"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-288","lang":"en","description":"CWE-288: Authentication Bypass Using an Alternate Path or Channel","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-306","lang":"en","description":"CWE-306: Missing Authentication for Critical Function","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-06-24T21:01:16.544Z"},"source":{"advisory":"GHSA-28mh-j262-q49w","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-06-25T13:22:04.810298Z","id":"CVE-2026-33543","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-06-25T13:22:14.263Z"}}]}}}