Three Low/Info hardening items from the 2026-06-10 security review.
OAuth/credential log redaction:
- oauth-flow.server.ts logged the raw exception on code-exchange
failure; a provider error can embed the auth code / token response,
which would land in logs + Sentry. Log only e.message now.
- manager.markNeedsRelink bounded the provider-supplied reason string
to 200 chars before logging.
Magic-link account enumeration:
- createMagicToken now returns null (instead of throwing "No account
found for this email") when no account matches; the login route
always responds { step: "magic-link-sent" }, minting a token and
sending mail only for a real account. The public login form can no
longer be used to probe which emails are registered. Registration's
email/username "already in use/taken" messages are intentionally
unchanged — standard signup UX, and the passkey ceremony can't be
made to fake-succeed.
Federation remote-document size cap:
- assertRemoteDocSize rejects an actor/outbox document over 4 MB once
serialized, applied in the ingest fetchJson seam. Fedify owns the
transfer (with its own SSRF + redirect limits) and our poll uses the
authenticated loader for secure-mode instances, so this is a
downstream guard on iteration/persistence, complementing the existing
per-poll item cap.
Tests: assertRemoteDocSize unit cases; a gated (FEDERATION_INTEGRATION=1)
integration test asserting an unsigned POST to /users/:u/inbox is
rejected with 401 — a regression guard for Fedify's signature
verification.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
The PKCE verifier cookie, state encoding, redirect-URI construction,
and code exchange were coordinated across three route handlers that
each knew part of the protocol. Two latent bugs lived in the gaps: a
push-initiated re-authorization skipped PKCE entirely (harmless today
only because the sole pusher, Wahoo, is not a PKCE provider), and the
push-resume callback path never cleared the spent verifier cookie.
oauth-flow.server.ts now owns the lifecycle: initiateOAuthFlow builds
the provider redirect (state + verifier cookie, on every entry path),
and completeOAuthFlow consumes the callback — state decode, verifier
recovery, code exchange, connection linking — returning a
discriminated result the route maps to redirects. The three routes are
thin adapters; the next OAuth provider reuses the flow, not the
pattern.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
