fix(csp): remove unsafe-inline from script-src and harden security headers by advikdivekar · Pull Request #876 · Priyanshu-byte-coder/devtrack

advikdivekar · 2026-05-23T14:39:34Z

What the problem was

src/app/layout.tsx injected a theme-initialisation <script> block via dangerouslySetInnerHTML. Because browsers block inline scripts under a Content-Security-Policy, any CSP on the site had to include script-src 'unsafe-inline' to let this script run. 'unsafe-inline' completely disables the browser's CSP protection against inline-script injection, meaning any DOM-based XSS vector — present or introduced later — executes without browser-level blocking, and can immediately call /api/auth/session to steal credentials. The site also had no security headers at all: no CSP, no X-Frame-Options, no X-Content-Type-Options.

What was changed and in which files

src/app/layout.tsx
Removed the dangerouslySetInnerHTML inline script entirely. The layout now reads the theme cookie from next/headers (server-side, zero JS required) and applies className="dark" directly on <html> before the page leaves the server. No inline script, no unsafe-inline dependency.

src/components/ThemeContext.tsx
Updated the theme provider to write a theme cookie (SameSite=Lax; path=/; max-age=1yr) via document.cookie on every theme change, in addition to the existing localStorage write. On mount, it reads the initial theme from document.documentElement.classList (which the server already set from the cookie) to stay in sync without triggering a DOM class swap. For first-time visitors with no cookie, it falls back to localStorage then prefers-color-scheme.

next.config.mjs
Added a headers() export that applies four security headers to every route:

Content-Security-Policy — script-src 'self' (no unsafe-inline), style-src 'self' 'unsafe-inline' (needed for Tailwind inline styles), img-src allows GitHub avatars, frame-ancestors 'none', base-uri 'self', form-action 'self'
X-Frame-Options: DENY — belt-and-suspenders clickjacking protection alongside frame-ancestors 'none'
X-Content-Type-Options: nosniff — prevents MIME-type sniffing attacks
Referrer-Policy: strict-origin-when-cross-origin — limits referrer leakage

Why this approach fixes the root cause

The root cause was the inline script itself. A nonce-based CSP would still require generating and injecting a nonce per request, adding significant complexity. The cookie approach eliminates the inline script entirely — the server reads a value it controls (the httpOnly-equivalent first-party cookie) and renders the correct class before the HTML is sent. No JavaScript runs before the page is interactive, and no CSP exception is needed. The frame-ancestors 'none' directive replaces the previously used 'self' value, since DevTrack has no legitimate embedding use case.

Steps to test

Run npm run dev and open the app
Toggle between light and dark mode — confirm it works without flash
Reload the page — confirm the correct theme is applied immediately with no flash (cookie is set; server applies the class)
Open a new browser session (no cookie) — page loads in light mode; toggling sets the cookie; reload persists the choice
In DevTools → Network → any page request → Response Headers, confirm:
- Content-Security-Policy contains script-src 'self' with no unsafe-inline
- frame-ancestors 'none' is present
- X-Frame-Options: DENY is present
- X-Content-Type-Options: nosniff is present
In DevTools → Console, confirm no CSP violation errors for normal page use
Run npm run type-check and npm run lint — both pass with no new errors

Edge cases covered

Returning users (cookie set): Server applies class; no client-side DOM swap; zero flash
New users (no cookie): Server renders light; client reads prefers-color-scheme on mount and updates immediately; cookie is written; next load has no flash
localStorage migration: Existing users who stored preference in localStorage will have it picked up on first visit (fallback path) and the cookie will be set
System preference respected: On first visit, dark system preference triggers dark mode client-side
SSR/hydration: suppressHydrationWarning on <html> is retained; server and client agree on the class because both derive it from the same cookie

Regressions

None. npm run type-check and npm run lint pass clean. All dashboard functionality is unaffected — the security headers apply only to the HTTP layer and the theme change is a refactor of the persistence mechanism with identical visible behaviour.

Closes #858

Please review and merge this under GSSoC 2026.

vercel · 2026-05-23T14:39:39Z

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github-actions · 2026-05-23T14:39:42Z

GSSoC Label Checklist 🏷️

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Priyanshu-byte-coder · 2026-05-24T09:09:17Z

Great work on this PR — the CSP hardening and token exposure fix are both important security improvements. Before merging, there are 6 more API routes that still use session.accessToken which will break once the session callback no longer populates it:

src/app/api/metrics/inactive-repos/route.ts
src/app/api/metrics/discussions/route.ts
src/app/api/metrics/contributions/daily/route.ts
src/app/api/metrics/contributions/hourly/route.ts
src/app/api/metrics/coding-activity-insights/route.ts
src/app/api/metrics/activity/route.ts

Please migrate these to use getGitHubAccessToken(req) (the same pattern as the 13 routes already in this PR) before merging. This ensures no routes break in production when session.accessToken is removed from the session callback.

Priyanshu-byte-coder · 2026-05-24T12:54:49Z

This PR has merge conflicts with main. Please rebase on the latest main branch and re-request review. The approach is approved — just needs conflict resolution.

advikdivekar · 2026-05-24T14:37:35Z

This PR has merge conflicts with main. Please rebase on the latest main branch and re-request review. The approach is approved — just needs conflict resolution.

yes working on it, almost done, raising PR in few mins

…lidation

Migrate all metrics API routes to retrieve the GitHub OAuth token server-side via getGitHubAccessToken(req) instead of reading the now-removed session.accessToken field. Covers contributions, prs, pr-review-time, streak, repos, repo-health, ci, and compare routes.

…headers Replace the dangerouslySetInnerHTML theme-init script in layout.tsx with a server-side cookie read so the dark class is applied on <html> before the page is sent to the browser. ThemeContext writes the theme cookie on every toggle so the server stays in sync. With no inline script remaining, next.config.mjs can declare a strict CSP with script-src 'self' and no unsafe-inline. Also adds frame-ancestors 'none', X-Frame-Options, DENY, X-Content-Type-Options, and Referrer-Policy headers. Closes Priyanshu-byte-coder#858

…etGitHubAccessToken Migrated 9 routes that still read the GitHub OAuth token from the client-exposed session object to getGitHubAccessToken(req), which reads the token from the server-side httpOnly JWT instead: - src/app/api/metrics/activity/route.ts - src/app/api/metrics/discussions/route.ts - src/app/api/metrics/inactive-repos/route.ts - src/app/api/metrics/coding-activity-insights/route.ts - src/app/api/metrics/contributions/daily/route.ts - src/app/api/metrics/contributions/hourly/route.ts - src/app/api/metrics/prs/route.ts - src/app/api/goals/sync/route.ts - src/app/api/users/search/route.ts No session.accessToken references remain in any API route.

…essToken migration session can be null when getServerSession returns without a valid session (token is authoritative now). Use optional chaining on session.gitlabToken and session.githubId/githubLogin accesses to satisfy the TypeScript strict-null check.

After migrating goals/sync to getGitHubAccessToken, the route now passes auth in the Playwright environment (JWT secret matches) and reaches the Supabase query. With placeholder credentials the DNS lookup for placeholder.supabase.co can stall, keeping loading=true past the 10s timeout and hiding the Goals heading. Two changes: - Add a mock for **/api/goals/sync so the POST is intercepted at the browser level, matching how all other API routes are handled - Set last_synced_at to now() on the mock goal so needsSync=false and handleSync is not triggered at all (belt-and-suspenders)

advikdivekar requested a review from Priyanshu-byte-coder as a code owner May 23, 2026 14:39

github-actions Bot added gssoc26 GSSoC 2026 contribution type:bug GSSoC type bonus: bug fix type:security GSSoC type bonus: security (+20 pts) labels May 23, 2026

github-actions Bot assigned advikdivekar May 23, 2026

Priyanshu-byte-coder mentioned this pull request May 24, 2026

fix(auth): stop exposing GitHub OAuth token in client-accessible session #874

Closed

This was referenced May 24, 2026

fix(security): validate and sanitize github usernames in API routes #866

Merged

fix: paginate commit fetch in weekly-summary and hourly endpoints #896

Merged

feat: add developer persona and smart insights widget #853

Merged

Priyanshu-byte-coder added level:advanced GSSoC: Advanced difficulty (55 pts) gssoc:approved GSSoC: PR approved for scoring labels May 24, 2026

advikdivekar force-pushed the fix/issue-858-csp-unsafe-inline branch from 601c978 to 9f8b7bb Compare May 24, 2026 15:28

advikdivekar added 5 commits May 24, 2026 21:10

fix(auth): implement server-side GitHub access token retrieval and va…

1f9576b

…lidation

advikdivekar force-pushed the fix/issue-858-csp-unsafe-inline branch from 22ab408 to e1f08c9 Compare May 24, 2026 15:41

github-actions Bot added the type:testing GSSoC type bonus: tests (+10 pts) label May 24, 2026

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fix(csp): remove unsafe-inline from script-src and harden security headers#876

fix(csp): remove unsafe-inline from script-src and harden security headers#876
advikdivekar wants to merge 6 commits into
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advikdivekar commented May 23, 2026

What the problem was

What was changed and in which files

Why this approach fixes the root cause

Steps to test

Edge cases covered

Regressions

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vercel Bot commented May 23, 2026

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github-actions Bot commented May 23, 2026

GSSoC Label Checklist 🏷️

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Priyanshu-byte-coder commented May 24, 2026

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