# CVE-2026-53645 — FOSSBilling

> As of 2026-07-07, CVE-2026-53645 is a High-severity (band derived from the CVSS v4.0 score, not stated by the CNA) vulnerability in FOSSBilling, CVSS v4.0 8.5, EPSS 0.2% (15.0th percentile). No Threadlinqs-tracked threat campaign has been attributed to CVE-2026-53645 as of 2026-07-07; the identifier is re-checked against the Threadlinqs threat corpus on every daily ingest.

**Last updated:** 2026-07-07

## What is CVE-2026-53645?

FOSSBilling is a free, open-source billing and client management system. Versions prior to 0.8.0 allow a low-privileged staff account to grant arbitrary module permissions to itself through the admin API, resulting in persistent privilege escalation. A staff user that only has `staff.create_and_edit_staff` 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. Restrict the `staff.create_and_edit_staff` permission to only highly trusted staff members and/or use a reverse proxy or WAF to restrict access to `/api/admin/staff/permissions_update` to specific trusted roles.

The record classifies CVE-2026-53645 under weakness class [CWE-269](https://intel.threadlinqs.com/cwe/CWE-269). 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 91 days ago.

## Severity and exploitation probability

- **CVSS v4.0 base score:** 8.5 — High (derived from score) (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:N/SC:H/SI:H/SA:L`)
- **EPSS (FIRST):** 0.2% probability of exploitation in the next 30 days, higher than 15.0% of all scored CVEs
- **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 4.9/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2026-07-06, last modified 2026-07-07

## Is CVE-2026-53645 being exploited?

It currently carries a trending score of 34 in the Threadlinqs vulnerability feed.

## Affected products and versions

- [FOSSBilling](https://intel.threadlinqs.com/vendors/fossbilling): FOSSBilling

## How to fix CVE-2026-53645

No vendor patch reference has been recorded for CVE-2026-53645 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.

## Threat activity tracking CVE-2026-53645

No threat campaign in the Threadlinqs corpus currently references CVE-2026-53645, in its CVE list or as an indicator. The linkage is recomputed from the live corpus on every daily ingest, so this section fills in as soon as a tracked campaign cites the identifier.

## Sources

Enriched from CVE.org, NVD, FIRST EPSS. Last verified by Threadlinqs on 2026-07-07. This product uses the NVD API but is not endorsed or certified by the NVD.

**Vendor advisory and patch**

- [github.com](https://github.com/FOSSBilling/FOSSBilling/security/advisories/GHSA-4hf7-xxxw-64rm)

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-53645
Full detection coverage and IOCs for threats exploiting CVE-2026-53645 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp