SEPTEMBER 17, 2026
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Case File

CVE-2026-43928

LOW · CVSS 2.3 EPSS 0.27% Public Exploit

Source: NVD + CISA KEV + EPSS · Published 2026-07-06 · Last synced 2026-08-05

CyberRota Analysis

AI-Generated

The PayPalEmail payment adapter in FOSSBilling versions prior to 0.8.0 is vulnerable as it accepts IPN callbacks without validating the credited amount against the invoice total, allowing clients to underpay invoices by up to $0.04. This could lead to financial discrepancies and potential revenue loss for merchants. Users of the PayPalEmail adapter should prioritize upgrading to version 0.8.0 and actively monitor transactions for inconsistencies.

Public Exploit Signal

A public exploit, PoC, GitHub repository or Metasploit reference was detected for this CVE.

GitHub PoC Links

Note: these links are listed for security research and verification purposes only.

CVE
CVE-2026-43928
Severity
LOW
CVSS
2.3
EPSS
0.27%

Original NVD 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.