DoS/quota guardrails for the unauthenticated local APIs:
* Body-size middleware rejects oversized requests (Content-Length) before they
are buffered/base64-decoded (NEXUS_MAX_REQUEST_MB, default 32).
* Document upload enforces a decoded-byte cap (NEXUS_MAX_UPLOAD_MB, default 20)
and a PDF page-count cap (NEXUS_MAX_PDF_PAGES, default 500) as backstops for
chunked bodies and pathological files.
* A counter-based in-flight limiter bounds concurrent chats and document
ingests (NEXUS_MAX_CONCURRENT_CHATS/UPLOADS), returning 429 when saturated;
the chat slot is held for the whole SSE stream and released on completion or
client disconnect.
* /models/pull gains an opt-in allowlist (NEXUS_MODEL_ALLOWLIST); empty by
default so behaviour is unchanged, otherwise a bare repo name permits all its
tags.
Co-authored-by: Cursor <cursoragent@cursor.com>
Two tool/agent-layer hardening changes:
* fetch_url now resolves the target host and refuses to connect if any
resolved address is loopback, private (RFC1918/ULA), link-local (incl. the
169.254.169.254 cloud-metadata endpoint), multicast, reserved, or
unspecified. IPv4-mapped IPv6 is unwrapped first, and the guard re-runs on
every redirect hop so a public URL cannot 302 its way to an internal target.
* /chat/approve now requires a single-use token minted when the stream pauses
for approval and delivered only in that stream's tool_request event, compared
in constant time. Previously the pending approval was keyed solely on a
client-supplied conversation_id, so anyone who could enumerate a
conversation_id could approve another client's pending action.
The frontend threads the token from the tool_request event into the approve
call.
Co-authored-by: Cursor <cursoragent@cursor.com>
The Synapse backend and memory service bound 0.0.0.0 with wildcard CORS and no
auth, exposing the full unauthenticated admin/data API to the LAN. Default the
uvicorn bind to 127.0.0.1 (NEXUS_BIND_HOST override), scope CORS to known local
origins instead of "*", and add TrustedHostMiddleware to reject foreign Host
headers (which defeats DNS-rebinding, something same-origin CORS cannot stop).
NEXUS_ALLOWED_HOSTS / NEXUS_ALLOWED_ORIGINS allow opt-in LAN exposure, intended
to be paired with real authentication.
Co-authored-by: Cursor <cursoragent@cursor.com>
AthenaandCursor
GitNexus · part of the Nexus stack