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.
CVE-2026-43928
This low-severity CVE scores 2.3 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.3%, top 81% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
- Lower severity and no public exploit yet
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 2.3
- EG Score
- 2.3(medium)
- EPSS
- 19.2%
- KEV
- Not listed
Published
July 6, 2026
Last Modified
July 7, 2026
References (2)
- security-advisories@githubhttps://github.com/FOSSBilling/FOSSBilling/security/advisories/GHSA-xjc6-g382-h942
- 134c704f-9b21-4f2e-91b3-4a467353bcc0https://github.com/FOSSBilling/FOSSBilling/security/advisories/GHSA-xjc6-g382-h942
Weakness Classification(2)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 7× in last 7d / 7× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
- 2026-07-11 08:27 UTCEPSS rescore
- 2026-07-09 19:49 UTCEG score recompute
- 2026-07-09 19:10 UTCEPSS rescore
- 2026-07-08 15:16 UTCEPSS rescore
- 2026-07-07 13:46 UTCEPSS rescore
- 2026-07-06 22:09 UTCEG score recompute
- 2026-07-06 22:09 UTCMITRE cvelistV5first tracked
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