GHSA-hp74-gm6m-2qm5

Pocket ID has a reauthentication bypass via one-time access token login — passkey step-up requirement defeated by JWT freshness check that accepts any login method

Published

2026-07-28

Modified

2026-07-28

Sources

github-advisory

Summary

# Reauthentication Bypass via One-Time Access Token Login ## Summary A weaker authentication method (OTA token or signup token) is accepted as passkey step-up proof, yielding unauthorized renewable 30-day OIDC refresh tokens for clients explicitly configured with `RequiresReauthentication: true`. The `POST /api/webauthn/reauthenticate` endpoint's access-token fallback checks only JWT freshness (`IssuedAt` within 60 seconds), not the authentication method used. The session cookie gate is also non-validating -- any arbitrary cookie value (e.g. `session=deadbeef`) is accepted, collapsing the reauth boundary to token recency alone. The bypass needs to succeed only once. The resulting OIDC grant includes a 30-day refresh token that can be rotated indefinitely, providing persistent victim-impersonation access to the protected downstream service. The attacker obtains `access_token` (1-hour TTL), `id_token` (victim's name, email, profile), and `refresh_token` (30-day TTL, renewable) for a client that was explicitly configured to require passkey step-up authentication. The attacker can perform victim-scoped actions at the downstream relying party indefinitely. ## Root Cause `CreateReauthenticationTokenWithAccessToken` (webauthn_service.go:362-403) only checks that the access token's `IssuedAt` claim is less than 60 seconds old: ```go // webauthn_service.go:378-381 tokenExpiration, ok := token.IssuedAt() if !ok || time.Since(tokenExpiration) > time.Minute { return "", &common.ReauthenticationRequiredError{} } ``` It does not check HOW the user originally authenticated. The `reauthenticateHandler` (webauthn_controller.go:179-207) falls into this path whenever the request body cannot be parsed as a WebAuthn credential assertion: ```go // webauthn_controller.go:189-199 credentialAssertionData, err := protocol.ParseCredentialRequestResponseBody(c.Request.Body) if err == nil { token, err = wc.webAuthnService.CreateReauthenticationTokenWithWebauthn(...) } else { // FALLBACK: Only checks access token age, not auth method accessToken, _ := c.Cookie(cookie.AccessTokenCookieName) token, err = wc.webAuthnService.CreateReauthenticationTokenWithAccessToken(c.Request.Context(), accessToken) } ``` Additionally, the handler's session cookie check (line 180) only verifies that a cookie named `session` exists -- it does not validate the cookie value against any server-side session store. Any arbitrary value (e.g. `session=deadbeef`) satisfies the check: ```go // webauthn_controller.go:180-184 sessionID, err := c.Cookie(cookie.SessionIdCookieName) if err != nil { _ = c.Error(&common.MissingSessionIdError{}) return } // sessionID is passed to CreateReauthenticationTokenWithWebauthn but NOT // to CreateReauthenticationTokenWithAccessToken (the fallback path) ``` In the fallback path, the `sessionID` variable is never used. The session cookie is a gate check only -- presence, not validity. This means the reauth boundary is not bound to a real authenticated browser session. Meanwhile, `GenerateAccessToken` (jwt_service.go:190-195) always sets `IssuedAt(now)` regardless of how authentication was performed: ```go // jwt_service.go:191-195 now := time.Now() token, err := jwt.NewBuilder(). Subject(user.ID). Expiration(now.Add(...)). IssuedAt(now). // Always "now" — regardless of auth method ``` This function is called by: 1. WebAuthn login (intended passkey path) 2. One-time access token exchange (one_time_access_service.go:200) 3. User signup (user_signup_controller.go:182) All three produce tokens that bypass the reauthentication freshness check. ## Attack Chain **Precondition**: An OIDC client has `RequiresReauthentication: true`. The attacker has obtained a one-time access token (via email compromise, admin-issued token, or if unauthenticated OTP emails are enabled). 1. **Exchange OTA for fresh JWT**: `POST /api/one-time-access-token/{token}` returns a fresh access token with `IssuedAt = now`. 2. **S

Affected packages

Remediation: Upgrade to 0.0.0-20260419162744-978ac87deffe or later.

References

• https://github.com/advisories/GHSA-hp74-gm6m-2qm5