CORS: never allow credentials for the wildcard origin - #53
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The parent app used allow_origins=['*'] with allow_credentials=True, which makes Starlette reflect any request Origin and add Access-Control-Allow-Credentials: true, so any page that got the browser to send the session cookie could read a signed-in user's responses. New PlatformConfig.cors_origins (platform.toml [platform]): ['*'] (default) allows any origin without credentials; an explicit list allows those origins with credentials; [] disables CORS. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Refuse "*" mixed with named origins (would silently drop credentials), "null" (any sandboxed page sends it), and values that are not scheme://host[:port] (never match, fail silently). Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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The platform-level CORS middleware was
allow_origins=["*"], allow_credentials=True. With that pair Starlette reflects the request'sOriginand addsAccess-Control-Allow-Credentials: true, so a page on another origin that gets the browser to attach the session cookie can read a signed-in user's responses (confirmed locally with a protected app behind enlace_auth).SameSite=Laxsession cookies limit which origins can do that in practice, but the header pair should never be sent for arbitrary origins.PlatformConfig.cors_origins([platform] cors_originsin platform.toml):["*"](default) — any origin, without credentials (public responses stay readable cross-origin, as before);[]— no CORS headers.cors_originsis validated:"*"must stand alone,"null"is refused, named origins must bescheme://host[:port].Independent refute-review done: no blockers; its should-fixes (
"null"re-opening exposure,"*"mixed with named origins, malformed origins silently never matching) are fixed in the second commit. Noted, not changed: auth middleware runs before CORS, so 401s carry no CORS headers (pre-existing); enlace_auth's/api/CSRF exemption relies on SameSite=Lax, which does not stop same-site sibling hosts.Behaviour change: cross-origin credentialed calls from arbitrary origins stop working unless the origin is listed. In-fleet frontends call the API same-origin (relative URLs), so nothing known depends on it.
Tests:
enlace/tests/test_cors.py(fail on main). Full suite 308 passed. Dependents against this branch: enlace_auth 377 passed, enlace_docker 58 passed / 2 skipped.🤖 Generated with Claude Code