CVEvulnerability

CVE-2026-111056

6.9 MEDIUM Published 2026-10-19 Modified 2026-10-22 Official page ↗
Status
Deferred
Published
2026-10-19
Last modified
2026-10-22
Assigner
[email protected]
CVSS 4.0 ([email protected])
6.9 MEDIUM — 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Weaknesses
CWE-200, CWE-204, CWE-307

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.

Related

Weakness · CWE (3)

  • CWE-200 Exposure of Sensitive Information to an Unauthorized Actor weakness
  • CWE-204 Observable Response Discrepancy weakness
  • CWE-307 Improper Restriction of Excessive Authentication Attempts weakness

References