PT-2026-56032 · Unknown · Fossbilling

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CVE-2026-43928

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Published

2026-07-06

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Updated

2026-07-07

CVSS v4.0

2.3

Low

VectorAV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:L/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
Name of the Vulnerable Software and Affected Versions FOSSBilling versions prior to 0.8.0
Description The PayPalEmail payment adapter fails to validate the amount supplied via PayPal IPN (Instant Payment Notification) callbacks, specifically the mc gross variable, against the actual invoice total. Due to a $0.05 floating-point epsilon tolerance—a small margin of error used in computer calculations to account for precision limits—in the invoice credit-payment logic, a client can underpay an invoice by up to $0.04 and still have the system mark it as fully paid.
Recommendations Update to version 0.8.0. Monitor IPN transactions for amounts that do not match corresponding invoice totals and manually review or refund suspicious payments.

Exploit

Fix

Improper Check for Exceptional Conditions

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Weakness Enumeration

Related Identifiers

CVE-2026-43928
GHSA-XJC6-G382-H942

Affected Products

Fossbilling