CVE-2026-42341Network attack vector

Unauthenticated payment bypass via forged IPN callbacks

Published Jul 6, 2026 · Updated Jul 6, 2026

Payment bypass in FOSSBilling 0.6.0 through 0.7.2 allows remote attackers to mark unpaid invoices as paid via crafted IPN callbacks. The ipn.php endpoint sets skip_validation, bypasses _parseIpnAndApprove(), and lets Custom::processTransaction() call addFunds() and markAsPaid() without authenticating the callback source. The Custom payment adapter must be enabled; successful requests alter invoice state, credit client balances, and can provision associated orders.

CVSS severity9.2
Critical
EPSS probability0.27%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Payment bypass in FOSSBilling 0.6.0 through 0.7.2 allows remote attackers to mark unpaid invoices as paid via crafted IPN callbacks. The ipn.php endpoint sets skip_validation, bypasses _parseIpnAndApprove(), and lets Custom::processTransaction() call addFunds() and markAsPaid() without authenticating the callback source. The Custom payment adapter must be enabled; successful requests alter invoice state, credit client balances, and can provision associated orders.

The record

CVE
CVE-2026-42341
Published
Jul 6, 2026
Updated
Jul 6, 2026
Vendor
FOSSBilling
Product
FOSSBilling
Classifications
CWE-346, CWE-306, T1565.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 6, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 6, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 0.6.0, < 0.8.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

FOSSBilling · FOSSBillingversion=>= 0.6.0, < 0.8.0

Published CVSS scores

9.2GitHubCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:H/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-346Origin Validation Error
CWE-306Missing Authentication for Critical Function
T1565.001Stored Data Manipulation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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