Vulnerability Analysis
FOSSBilling has an unauthenticated payment bypass via IPN callback forgery
CVE-2026-42341
FOSSBilling is a free, open-source billing and client management system. Versions 0.6.0 through 0.7.2 have an unauthenticated payment bypass vulnerability in FOSSBilling's IPN callback endpoint. When the Custom payment adapter is enabled, an attacker can mark any unpaid invoice as paid and credit the associated client account without making an actual payment, by sending a single crafted HTTP request. Version 0.8.0 patches the issue. Some workarounds are available. Disable the Custom payment gateway if not actively needed and/or restrict access to `/ipn.php` at the web server level (e.g., via IP allowlisting), noting that this may interfere with legitimate payment callback processing.
No Active Exploit Signals
CVSS Base Score
9.2
CRITICAL
Exploitability:-
Impact Score:-
Temporal Score:-
EPSS:0.18%
Threat Intelligence Signals
CISA KEV
No
KEV Date Added
—
Ransomware Use
—
KEV Due Date
—
VulnCheck In-the-Wild
No
Nuclei Template
No
EPSS Score
0.184%
EPSS Percentile
8.1th pct
GHSA ID
—
GitHub Severity
—
SSVC Exploitation
None
SSVC Automatable
Yes
Vulnerability Class
—
Identity & Timeline
| Status | - |
| Assigning Authority | - |
| CVSS Version / Source | - |
| Reserved | - |
| Published | - |
| Patch Date (date_public) | - |
| Exploit DB Date | - |
| First GitHub PoC Date | - |
| Last Updated | - |
| Time to Patch (Days to fix) | - |
| Exploit Release Gap | - |
| PoC Release Gap | - |
| Exploit DB References | None identified |
Affected Products & Versions
| Vendor | Product | Affected Versions |
|---|---|---|
| No affected products specified. | ||
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