How to report a security issue privately? (Security Advisories page 404s)

[novice-22]

Hi! I'd like to privately report a potential security issue in portal-mcp-server,
following SECURITY.md. The linked Security Advisories page (/security/advisories/new)
returns 404 — Private Vulnerability Reporting looks disabled — and I couldn't find a
contact email.
Could you either:

1. Enable Private Vulnerability Reporting (Settings → Code security→"Private
   vulnerability reporting"), or
2. share a private contact?

I'll send full details + a PoC through whichever channel you prefer. I'm intentionally
omitting specifics here to avoid public disclosure. Thanks!