{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "0.1.0"
              },
              {
                "fixed": "0.8.7"
              }
            ],
            "source": "AFFECTED_FIELD"
          },
          "events": [
            {
              "introduced": "469046158e66d47fa4976703657016961abff3a1"
            },
            {
              "fixed": "29cd19d8793747e86b59a033688e5b9b83de8fab"
            }
          ],
          "repo": "https://github.com/fossbilling/fossbilling",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-x4mh-g4pc-wfc5"
  ],
  "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"
  },
  "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.",
  "id": "CVE-2026-111056",
  "modified": "2026-10-20T02:30:24.437301930Z",
  "published": "2026-10-19T16:00:57.576Z",
  "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"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "FOSSBilling: Unauthenticated client account enumeration via guest signup endpoint"
}