Cap-go capgo.app up to 1.0.0/1.0.1 JWT Middleware hono_middleware.ts foundJWT improper authentication

Summaryinfo

A vulnerability was found in Cap-go capgo.app up to 1.0.0/1.0.1 and classified as critical. This vulnerability affects the function foundJWT of the file supabase/functions/_backend/utils/hono_middleware.ts of the component JWT Middleware. The manipulation results in improper authentication. This vulnerability is reported as CVE-2026-88861. The attack can be launched remotely. No exploit exists.

Detailsinfo

A vulnerability, which was classified as critical, was found in Cap-go capgo.app up to 1.0.0/1.0.1. Affected is the function foundJWT of the file supabase/functions/_backend/utils/hono_middleware.ts of the component JWT Middleware. The manipulation with an unknown input leads to a improper authentication vulnerability. CWE is classifying the issue as CWE-287. When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is available at github.com. This vulnerability is traded as CVE-2026-88861 since 09/10/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. Technical details are known, but there is no available exploit. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 09/10/2026).

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

If you want to get best quality of vulnerability data, you may have to visit VulDB.

Productinfo

Vendor

• Cap-go

Name

• capgo.app

Version

• 1.0
• 1.0.0
• 1.0.1

Website

• Product: https://github.com/Cap-go/capgo.app/

CPE 2.3info

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If you want to get best quality of vulnerability data, you may have to visit VulDB.

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