Closes#282. CLAUDE.md documented the SecurityHeaders() middleware as
setting 6 headers (X-Content-Type-Options, X-Frame-Options, Referrer-
Policy, Content-Security-Policy, Permissions-Policy, HSTS) but the
implementation only set 4 — Referrer-Policy and Permissions-Policy
were silently missing.
Adds:
- Referrer-Policy: strict-origin-when-cross-origin — prevents
browsers from leaking full paths/queries in Referer on cross-
origin navigation. Particularly relevant for canvas embeds of
Langfuse trace URLs that may contain trace IDs.
- Permissions-Policy: camera=(), microphone=(), geolocation=() —
denies sensor access by default. Iframes the canvas embeds
(Langfuse trace viewer etc.) can no longer request these
without an explicit delegation.
Regression tests added to securityheaders_test.go — both headers
are now in the same table-driven assertion loop as the other 4,
so a future edit that drops them again fails CI loudly.
LOW severity — this is defense-in-depth, not a direct exploit path.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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