Please report security issues privately — do not open a public issue for a suspected vulnerability. Use GitHub's Report a vulnerability (Security → Advisories) or email the maintainer. You'll get an acknowledgement, and a fix or mitigation will be coordinated before public disclosure.

• Tenant isolation is enforced server-side: API keys are locked to an org, and viewers are scoped to their org by verified identity. Cross-org reads/writes 404.
• Viewer identity is intended to run behind Cloudflare Access. When CF_ACCESS_TEAM_DOMAIN + CF_ACCESS_AUD are set the app verifies the Access JWT, so identity/org cannot be spoofed. With those unset the app fails closed — no request can obtain a viewer/admin identity from a header. Header trust is an explicit loopback-only dev opt-in (TRUST_ACCESS_HEADERS=1) that additionally refuses to start on a non-loopback bind. Set the JWT vars in production.
• Untrusted artifact content is served with a CSP sandbox (no allow-same-origin) on every raw/download/share response, so it runs in a null origin. In addition, every cookie-authenticated portal mutation requires a first-party X-Artifact-Mutation: 1 header and same-origin browser metadata (or a canonical Origin fallback). This closes the otherwise possible artifact-iframe → administrator-action forgery: sandboxed artifact JavaScript can issue a credentialed no-cors request, but cannot attach the non-simple portal header. /mcp uses explicit bearer authentication and is not an ambient-cookie surface.
• Public share links (/s/:token) are opt-in, read-only, noindex, no-store, and gated only by an unguessable token — treat them as "anyone with the link." They rely on a Cloudflare Access Bypass on /s/*.
• Webhooks are validated to the Discord host (no SSRF to arbitrary hosts) and delivered fire-and-forget without following redirects.
• Not included: content scanning, rate limiting, and a physically separate raw-content origin. Run the service on a dedicated hostname.

This is a young project; security fixes target the main branch. Pin a commit if you need stability and watch releases for advisories.