Triage of an external SAST/SCA scan run on 2026-05-06. Most loud findings
were already resolved by PR #412 (the 18-CVE backport); this PR addresses
the residual real items:
* Drop unused `handlebars` from backend deps. The runtime require was
removed in PR #367 (#367) but the package.json line stayed. handlebars
was the source of two flagged criticals (CVE-2026-33937 RCE,
GHSA-2w6w-674q-4c4q AST injection) plus 8 highs — all now gone.
* `npm audit fix` on backend + frontend. Bumps transitive picomatch,
flatted, postcss, brace-expansion via lockfile, and direct dompurify,
lodash, vite, i18next-http-backend within their existing semver ranges.
Both audits now report 0 vulnerabilities.
* Add `event.origin === window.location.origin` check to the THEME_PREVIEW
message listener in PreviewPage. The branding page posts from the same
origin, so nothing legitimate is rejected; without the check, any third
party that window.open()'d the preview could push arbitrary
branding/theme payloads (semgrep
insufficient-postmessage-origin-validation).
* nginx: `proxy_hide_header` for X-Frame-Options, X-Content-Type-Options,
Referrer-Policy, Content-Security-Policy, Permissions-Policy,
Strict-Transport-Security at server level. nginx adds these itself, but
helmet on the backend was also emitting them — clients were seeing
duplicates (testssl flagged "Multiple X-Frame-Options / CSP /
Permissions-Policy / Referrer-Policy headers" on the live origin).
Single source of truth now.
* Dockerfile hardening (checkov):
- HEALTHCHECK on backend/Dockerfile, backend/Dockerfile.dev,
frontend/Dockerfile.dev. Frontend production Dockerfile already had
one.
- USER node in frontend/Dockerfile.dev (was running as root).
* GitHub Actions docker-build.yml: explicit top-level
`permissions: contents: read`. Per-job blocks already declare
`packages: write` where needed; this stops future steps from
inheriting unintended privileges (CKV2_GHA_1).
Backend npm audit: 4 vulns -> 0.
Frontend npm audit: 6 vulns -> 0.
Backend unit tests: 13 suites, 131/132 passing (1 pre-existing skip).
Frontend type-check + lint: clean.
The pre-existing integration-test failures (live DB / S3 required) and
the ThemeCustomizerEnhanced QueryClientProvider failures are unrelated
and reproduce on origin/beta without these changes.
Paul Nothaft
6b6191a426