EUVD-2026-41962Severity by source
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:L/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
Network-reachable registration endpoint, no auth required; impact is limited integrity only (group field injection), with no confidentiality or availability effect and unchanged scope.
Primary rating from Vendor (github).
CVSS VectorVendor: github
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:L/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
Lifecycle Timeline
2DescriptionCVE.org
FOSSBilling is a free, open-source billing and client management system. Prior to version 0.8.0, an unauthenticated mass assignment vulnerability in the client self-registration endpoint allows any visitor to assign themselves to an arbitrary client group during sign-up. Because client groups can gate promo code eligibility, an attacker may apply group-restricted discount codes and receive unauthorized discounts. Version 0.8.0 contains a patch. As a workaround, administrators can either remove group restrictions from promo codes or disable client self-registration (Settings → Clients → Disable signup).
AnalysisAI
Unauthenticated mass assignment in FOSSBilling's client self-registration endpoint (all versions prior to 0.8.0) allows any visitor to inject an arbitrary client group identifier during signup, bypassing group-based access controls on promotional codes. Attackers who successfully place themselves into a privileged group can redeem group-restricted discount codes and receive unauthorized price reductions. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires two simultaneous conditions: (1) client self-registration must be enabled in FOSSBilling settings - the administrator-documented workaround to 'Disable signup' implies this is an operator-configurable state, not necessarily the default; and (2) at least one promotional code must be configured with client group eligibility restrictions, such that the target group grants access to codes unavailable to the default new-client group. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:N/UI:N) confirms that exploitation is network-accessible, requires no authentication, no special attack conditions, and no user interaction - maximizing accessibility. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An unauthenticated attacker visits the FOSSBilling public registration page and submits a crafted HTTP request to the signup endpoint that includes an extra parameter setting the client group to a privileged or restricted group known to gate promotional codes. The newly created account is silently placed in that group, and the attacker immediately redeems a group-restricted promotional code to obtain an unauthorized discount on a purchase. … |
| Remediation | Upgrade to FOSSBilling version 0.8.0, which contains the vendor-confirmed patch for this mass assignment vulnerability; the advisory at https://github.com/FOSSBilling/FOSSBilling/security/advisories/GHSA-q4rq-9844-r9w2 should be consulted for release details. … Detailed patch versions, workarounds, and compensating controls in full report. |
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