Vulnerability · Published Sep 10, 2026 · Assigned by VulnCheck
CVE-2026-88861Capgo AAL1 Session MFA Bypass via Direct RBAC Authorization
High 8.3
In plain English
A high-severity authentication bypass in capgo.app from Cap-go. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 45% of all known vulnerabilities). Ready-made attack tooling exists: public proof-of-concept code.
Official description
Capgo (Cap-go/capgo.app) contains an authentication bypass affecting all versions (no patched version available at time of publication). The Edge authorization path allows a password-only Supabase aal1 session to exercise privileged RBAC permissions even when the account has a verified MFA factor that has not been used for the session: the Edge JWT middleware (foundJWT() in supabase/functions/_backend/utils/hono_middleware.ts) accepts the JWT without validating its assurance level, and the direct RBAC path (checkPermission()/checkPermissionPg() in supabase/functions/_backend/utils/rbac.ts calling public.rbac_check_permission_direct()) authorizes by user ID without passing or checking the session aal, unlike the public.verify_mfa() control which correctly requires aal2. An attacker who knows only the victim's password can therefore authenticate, mint a persistent app-scoped app_admin API key that remains valid after the aal1 session is logged out, and perform privileged operations such as modifying production OTA channel configurations (validated by changing a public production channel from bundle 1.0.0 to 1.0.1), defeating the protection provided by MFA.
Affected products (as reported)
Weakness: CWE-288 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:L
References
- GitHub Security Advisory (GHSA-9435-5xw9-v29h) vendor-advisory
- VulnCheck Advisory: Capgo AAL1 Session MFA Bypass via Direct RBAC Authorization third-party-advisory