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CVE-2026-27604 is an improper authorization vulnerability in FOSSBilling versions 0.5.4 through 0.7.2, and versions before 0.8.0. API role validation constructs an exception for an invalid role but fails to throw it. Consequently, an unauthenticated caller can select the internal system API role, which resolves to the privileged cron identity and bypasses normal administrative permission checks. This permits access to privileged administrative API methods without credentials, an authenticated session, or a CSRF token.
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1 valid exploit after Mallory filtered fakes, detection scripts, and README-only repos.
This 16-file repository is a local Docker reproduction and debugging lab for a claimed FOSSBilling pre-authentication RCE chain combining CVE-2026-27604 (API role/authentication bypass) and CVE-2026-28496 (unsandboxed Twig SSTI). Docker Compose builds a vulnerable FOSSBilling 0.7.2 container on localhost:8081, a patched 0.8.0 comparison container on localhost:8082, and separate MariaDB/install-helper services. The sole active exploit-style client, scripts/trigger-debug.py, sends POST /api/system/system/string_render with {"_tpl":"{{ 7*7 }}"}; it optionally triggers Xdebug for source-level tracing. The documentation explains that role system improperly resolves to a cron-admin identity and passes _tpl to Twig rendering. The repository provides only an arithmetic SSTI proof, not an RCE gadget or malicious payload. Shell scripts automate lab installation and debugging, while Dockerfiles configure images; no external targets, callbacks, web shells, persistence, or data-exfiltration code are present.
5 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
The content only identifies CVE-2026-27604 in connection with adding a template; it provides no technical details about the affected product, vulnerability type, impact, or remediation.
An authentication bypass in FOSSBilling caused by a missing throw statement in the API role checker, allowing unauthenticated attackers to access privileged /api/system/ endpoints and invoke admin functionality.
An authorization bypass vulnerability in FOSSBilling API role handling that allows unauthenticated attackers to access privileged admin `/api/system/*` endpoints by resolving `system` to the cron admin identity.
An authentication bypass in FOSSBilling caused by a missing throw keyword in API role validation, allowing unauthenticated access to privileged /api/system/ endpoints and enabling full compromise when chained with CVE-2026-28496.
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