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Vulnerabilities

Security incident · CVE-2026-43924

FOSSBilling is a free, open-source billing and client management system.

Published Jun 3, 2026 · catalog updated Jul 22, 2026 · FOSSBilling is a free,

Check if you run it

No confirmed exploitation is on record for CVE-2026-43924. EPSS is 0.44%. Act only if a listed version of FOSSBilling is a free, is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (FOSSBilling is a free,).
  • No version range is stored. A customer cannot check an installed version against this record.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Medium4.8
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.44%
Remediation
Advisory link
Affected products
See sources for product scope

FOSSBilling is a free, open-source billing and client management system. Prior to version 0.8.0, the Redirect module does not validate the URL scheme of administrator-configured destination URLs before storing or issuing redirects. This allows arbitrary external URLs to be configured as redirect targets, creating an open redirect vulnerability exploitable for phishing attacks. Users following a legitimate FOSSBilling URL can be silently redirected to an attacker-controlled external site. The redirect is issued as a 301 (Moved Permanently) response, which browsers cache persistently, amplifying the impact. Exploitation requires administrator privileges to create or modify redirect entries, limiting practical attack scenarios to multi-admin environments or compromised admin accounts. Version 0.8.0 fixes the issue. Some workarounds are available. Restrict admin access to the Redirect module to trusted administrators only and/or audit existing redirect entries in the database (the table with ) for any unexpected or external target URLs.

No affected version ranges are stored yet. Use the vendor advisory before you decide this record does not apply.

How to fix CVE-2026-43924

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-43924. EPSS is 0.44%. Act only if a listed version of FOSSBilling is a free, is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-601: URL Redirection to Untrusted Site (Open Redirect). EPSS 0.44%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Jun 3, 2026 · NIST NVD

    Detected

    FOSSBilling is a free, open-source billing and client management system. Prior to version 0.8.0, the Redirect module does not validate the URL scheme of administrator-configured destination URLs before storing or issuing redirects. This allows arbitrary external URLs to be configured as redirect targets, creating an open redirect vulnerability exploitable for phishing attacks. Users following a le

  2. Jul 22, 2026 · NIST NVD

    Updated

    FOSSBilling is a free, open-source billing and client management system. Prior to version 0.8.0, the Redirect module does not validate the URL scheme of administrator-configured destination URLs before storing or issuing redirects. This allows arbitrary external URLs to be configured as redirect targets, creating an open redirect vulnerability exploitable for phishing attacks. Users following a le

Sources

  • CVE.orgVulnerability recordCVE-2026-43924

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-43924

    30-day exploitation probability 0.4%

    first.org
  • NIST NVDVulnerability recordCVE-2026-43924

    FOSSBilling is a free, open-source billing and client management system. Prior to version 0.8.0, the Redirect module does not validate the URL scheme of administrator-configured destination URLs before storing or issuing redirects. This allows arbitrary external URLs to be config

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.