AI & Agent Dev Bug Sandbox Back to Radar

Account Locked In 2FA Loop When MFA Was Never Enabled

Users with Pro accounts are unable to log in because Supabase Auth repeatedly requests a second factor (TOTP) despite no MFA factors being enrolled for the user. This locks the account in a loop after email/password authentication.

criticalConfidence 60%GoTrue

Origin Analysis

In GoTrue, the `aal` claim in the access token is incorrectly set to `aal2` even when the user has no enrolled MFA factors. The client interprets the `aal2` requirement as a need to perform MFA verification, redirecting to the MFA challenge. Since the user has no factor to verify, the loop continues indefinitely.

1. Sign up for Supabase Pro account without enabling MFA.\n2. Log out and attempt to sign in with email and password.\n3. Observe that after submitting password, the application prompts for a 6-digit TOTP code.\n4. Because no TOTP factor is enrolled, the user cannot provide a valid code and is stuck.

Fixing Code Block

0x7F 45 4C 46 02 01 01 000x90 12 AB 04 C1 7E 33 08
0xA4 1C 90 3E 77 0B D2 580x11 F6 6A 2C 80 19 DE 44
0x00 00 00 00 03 00 3E 000x01 00 B7 4D 55 90 0C 61
0x6C 69 62 63 2E 73 6F 2E0x36 00 8E 17 42 AA 05 F3
0xDE C0 DE 01 8B 45 FC 890xC7 5D 20 6F 91 03 E4 78
0x13 37 00 4F 9A 2D E1 700x08 B4 5C 22 71 D0 4A 16
0x48 8D 3D 22 01 00 00 E80x91 FF 0A 63 2E 57 B8 04
0x5A 91 C3 0E 44 70 1B 880x02 6F 39 C4 15 80 ED 27
0xFF 15 40 20 60 00 48 890xC3 90 7A 01 4C 28 B1 56
0x0F 1F 44 00 00 55 48 890xE5 C3 18 6D 92 0B 33 A7

Edge Case Audit

This hotfix may inadvertently downgrade sessions for users with active MFA if `HasFactors()` implementation changes or if factors are not yet loaded; ensure to test with users who have enrolled TOTP. Rollback by reverting the patch and redeploying GoTrue. For already locked accounts, administrators should manually disable MFA via the `supabase.auth.admin.deleteFactor` API or by clearing `auth.mfa_factors` for the affected user before applying the patch.