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PatchSiren cyber security CVE debrief

CVE-2026-43925 FOSSBilling CVE debrief

CVE-2026-43925 is a medium-severity vulnerability in FOSSBilling, a free, open-source billing and client management system. An unauthenticated mass assignment vulnerability in the client self-registration endpoint allows any visitor to assign themselves to an arbitrary client group during sign-up. This could enable an attacker to apply group-restricted discount codes and receive unauthorized discounts. The vulnerability was patched in version 0.8.0. As a workaround, administrators can either remove group restrictions from promo codes or disable client self-registration. Defenders should prioritize upgrading to version 0.8.0 or later.

Vendor
FOSSBilling
Product
Unknown
CVSS
MEDIUM 6.9
CISA KEV
Not listed in stored evidence
Original CVE published
2026-07-06
Original CVE updated
2026-07-07
Advisory published
2026-07-06
Advisory updated
2026-07-07

Who should care

Administrators and users of FOSSBilling, especially those using client groups to manage promo code eligibility, should be aware of this vulnerability and take necessary actions to protect their systems. Operators, platform administrators, and security teams should review FOSSBilling deployments and apply patches or workarounds.

Technical summary

The vulnerability exists in the client self-registration endpoint of FOSSBilling, allowing unauthenticated users to assign themselves to arbitrary client groups. This is possible due to a mass assignment vulnerability. Client groups can be used to gate promo code eligibility, which an attacker could exploit to receive unauthorized discounts. The issue was addressed in version 0.8.0 with a patch. Affected deployments should prioritize upgrading to version 0.8.0 or later.

Defensive priority

Medium

Recommended defensive actions

  • Upgrade to FOSSBilling version 0.8.0 or later
  • Remove group restrictions from promo codes
  • Disable client self-registration
  • Review compensating controls for exposed systems while remediation is scheduled and verified
  • Check relevant monitoring, detection, and logs for exposed assets that need extra review
  • Track exceptions, retest remediated assets, and close the item only after evidence is documented
  • Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record was published on 2026-07-06T22:16:49.963Z and was last modified on 2026-07-07T15:16:47.183Z. The NVD entry is currently Deferred. Evidence is limited to CVE and NVD details. Defenders should verify FOSSBilling version and client group configurations.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-43925 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-43925

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-43925 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-43925

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.