Description
FOSSBilling is a free, open-source billing and client management system. Prior to version 0.8.0, the PayPalEmail payment adapter accepts PayPal IPN callbacks and credits the IPN-supplied amount (`mc_gross`) to the client's balance without validating it against the invoice total. Combined with a $0.05 floating-point epsilon tolerance in the invoice credit-payment logic, this allows a client to underpay an invoice by up to $0.04 and still have it marked as fully paid. Version 0.8.0 patches the issue. There is no effective workaround without modifying the source code. Merchants using the PayPalEmail adapter should monitor IPN transactions for amounts that do not match their corresponding invoice totals, and manually review and refund suspicious payments.
Published: 2026-07-06
Score: 2.3 Low
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

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Tracking

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History

Tue, 07 Jul 2026 00:15:00 +0000

Type Values Removed Values Added
First Time appeared Fossbilling
Fossbilling fossbilling
Vendors & Products Fossbilling
Fossbilling fossbilling

Mon, 06 Jul 2026 22:15:00 +0000

Type Values Removed Values Added
Description FOSSBilling is a free, open-source billing and client management system. Prior to version 0.8.0, the PayPalEmail payment adapter accepts PayPal IPN callbacks and credits the IPN-supplied amount (`mc_gross`) to the client's balance without validating it against the invoice total. Combined with a $0.05 floating-point epsilon tolerance in the invoice credit-payment logic, this allows a client to underpay an invoice by up to $0.04 and still have it marked as fully paid. Version 0.8.0 patches the issue. There is no effective workaround without modifying the source code. Merchants using the PayPalEmail adapter should monitor IPN transactions for amounts that do not match their corresponding invoice totals, and manually review and refund suspicious payments.
Title FOSSBilling: Payment amount not validated in PayPalEmail adapter allows invoice underpayment
Weaknesses CWE-1284
CWE-754
References
Metrics cvssV4_0

{'score': 2.3, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N'}


Subscriptions

Fossbilling Fossbilling
cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-07-06T21:53:31.172Z

Reserved: 2026-05-04T16:59:09.089Z

Link: CVE-2026-43928

cve-icon Vulnrichment

No data.

cve-icon NVD

No data.

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-07-07T00:00:12Z

Weaknesses
  • CWE-1284

    Improper Validation of Specified Quantity in Input

  • CWE-754

    Improper Check for Unusual or Exceptional Conditions