VulnerabilityDeferred

CVE-2026-42341

Versions 0.6.0 through 0.7.2 have an unauthenticated payment bypass vulnerability in FOSSBilling's IPN callback endpoint.

CRITICAL 9.2EPSS 0.27%

Does this matter?

High impact if exploited, but EPSS currently rates exploitation as unlikely (0.27%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.

Description

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.

CVSS 4.0: 9.2 CRITICALCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M
EPSS: 0.27% probability · 20th percentile
CISA KEV: Not listed
Weakness: CWE-306, CWE-346
Source: security-advisories@github.com

References

https://github.com/FOSSBilling/FOSSBilling/security/advisories/GHSA-5493-9m76-2qrr

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.