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CVE-2026-53645 FOSSBilling CVE debrief

CVE-2026-53645 is a high-severity vulnerability in FOSSBilling versions prior to 0.8.0. The issue allows a low-privileged staff account to grant arbitrary module permissions to itself through the admin API, resulting in persistent privilege escalation. A staff user with only `staff.create_and_edit_staff` permission can call `/api/admin/staff/permissions_update` targeting their own account and write any permission structure, bypassing the intended role-based access control boundary. Version 0.8.0 patches the issue. Some workarounds are available, such as restricting the `staff.create_and_edit_staff` permission to only highly trusted staff members and/or using a reverse proxy or WAF to restrict access to `/api/admin/staff/permissions_update` to specific trusted roles.

Vendor
FOSSBilling
Product
Unknown
CVSS
HIGH 8.5
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

System administrators and security teams responsible for FOSSBilling installations, especially those with low-privileged staff accounts, should be aware of this vulnerability and take immediate action to patch or mitigate it.

Technical summary

The vulnerability exists in FOSSBilling versions prior to 0.8.0, where a low-privileged staff account can escalate privileges through the admin API. The issue arises from inadequate role-based access control in the `/api/admin/staff/permissions_update` endpoint, allowing a staff user with `staff.create_and_edit_staff` permission to modify their own permissions and bypass intended access controls. This can be mitigated by restricting the `staff.create_and_edit_staff` permission to highly trusted staff members, using a reverse proxy or WAF to limit access to `/api/admin/staff/permissions_update`, and monitoring for suspicious activity related to staff account privilege escalation.

Defensive priority

High

Recommended defensive actions

  • Apply the patch by upgrading to FOSSBilling version 0.8.0 or later
  • Restrict the `staff.create_and_edit_staff` permission to only highly trusted staff members
  • Use a reverse proxy or WAF to restrict access to `/api/admin/staff/permissions_update` to specific trusted roles
  • Monitor for suspicious activity related to staff account privilege escalation
  • Perform regular inventory checks to ensure all FOSSBilling installations are up-to-date

Evidence notes

The CVE record was published on 2026-07-06T23:16:56.493Z and was last modified on 2026-07-07T14:16:32.857Z. The NVD entry is currently Deferred. The vulnerability has a CVSS score of 8.5 and is classified as HIGH severity.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-53645 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-53645

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

  • CVE-2026-53645 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-53645

    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.