Django security

Django Security

When to use

This skill is the Django-specific layer on top of secure-coding. Use it when Django gets in its own way: defaults that invite misunderstanding, ORM paths that look safe but still allow SQLi, or settings that may go wrong per environment.

Triggers on:

• A question like "review this Django app", "is our deploy safe", "what are our SECURE_ settings", "are we using CSRF correctly", "Django admin hardening".
• Presence of manage.py, settings.py, urls.py, models.py, views.py, Django middleware class paths in MIDDLEWARE, DRF viewsets.py or serializers.py.
• A PR that introduces @csrf_exempt, |safe, mark_safe, .raw(), .extra(), RawSQL, or HttpResponse(user_input).
• Django version bumps that are a security release (release notes will explicitly mention fixes).
• A handoff from security-review where Django is in the stack.

When NOT (handoff)

• General Python secure-coding (not Django-specific) → secure-coding.
• DRF as an API layer overlaps heavily with api-security: OAuth/JWT flow, OWASP API Top 10 belong there. Django-specific DRF foot-guns (e.g. HyperlinkedModelSerializer authorization bypass) stay here.
• SAST tool config (Bandit, Semgrep p/django) → sast-orchestrator.
• Dep vulns in Django or third-party packages → cve-triage.
• Deploy infrastructure (nginx, gunicorn, containers) → container-hardening / iac-security.
• Secrets handling (SECRET_KEY, DB creds) → secrets-scanner.

Approach

Six phases. Django defaults are reasonably safe; most issues arise where you deliberately override them.

1. Settings and deploy checklist

python manage.py check --deploy is a Django-built-in checker. Always run it, fix every warning before production. Not sufficient, but necessary.

Critical settings:

• DEBUG = False in production. DEBUG = True leaks stack traces, env vars, SQL queries: full app-internal exposure. No exceptions.
• ALLOWED_HOSTS explicit. Wildcard ['*'] in prod is a Host-header-injection vector.
• SECRET_KEY from environment or vault, never in source. Rotation schedule on suspicion of leak. See secrets-scanner.
• SECURE_SSL_REDIRECT = True, SECURE_HSTS_SECONDS >= 31536000 with SECURE_HSTS_INCLUDE_SUBDOMAINS and SECURE_HSTS_PRELOAD, SESSION_COOKIE_SECURE = True, CSRF_COOKIE_SECURE = True. Only where TLS is guaranteed.
• SESSION_COOKIE_HTTPONLY = True (default), SESSION_COOKIE_SAMESITE = 'Lax' or 'Strict'.
• SECURE_CONTENT_TYPE_NOSNIFF = True, SECURE_REFERRER_POLICY explicitly set.
• CSRF_TRUSTED_ORIGINS with full scheme+host where relevant (Django 4+).
• PASSWORD_HASHERS with Argon2 first, then PBKDF2 as fallback. Requires django-argon2 package.
• Database: ATOMIC_REQUESTS where appropriate, separate DB user with least privilege (no DROP/CREATE rights for the web user).

2. ORM and SQL injection

Django's ORM parameterizes by default. SQLi arises in places where you step out of it:

• .raw(): string formatting in the raw queryset gives SQLi. Use placeholder params: Model.objects.raw('SELECT * FROM app_model WHERE name = %s', [name]). Not f'SELECT ... WHERE name = {name}'.
• .extra(): deprecated, still widely used. where=, params=, select= can be abused. Prefer to replace with Func(), RawSQL() with params, or annotate() with ExpressionWrapper.
• RawSQL: parameter list MUST be used. The example in the Django docs shows RawSQL("select col from sometable where othercol = %s", (someparam,)). Follow that.
• QuerySet.annotate() / aggregate() with dict keys from user input. Historically vulnerable (see CVE-2022-28346, SQL injection via column aliases in dict keys). Reviewer rule: dict keys in annotate/aggregate never come from user input, hardcode them.
• Order-by with user input. .order_by(request.GET.get('sort')) lets users pick columns. Allowlist permitted column names.
• __in= with large lists from user input: not SQLi but still DoS. Cap list size.

Django CVE references (within a 3-year window, verify against release notes):

• CVE-2022-28346: QuerySet.annotate/aggregate SQLi via dict keys. Fixed in Django 2.2.28, 3.2.13, 4.0.4. Canonical example of "the ORM is safe, except when ..."
• CVE-2023-43665: Truncator DoS via crafted HTML. Fixed in 3.2.22, 4.1.12, 4.2.6.
• More recent CVEs in the Django 4.2/5.x series: [verify against https://docs.djangoproject.com/en/dev/releases/security/] for the current window.

3. Template injection and XSS

Django templates have autoescape on by default. XSS arises when you turn it off.

• {{ user_input|safe }}: renders raw HTML. Apply only to content you have controlled yourself (e.g. sanitized HTML from a trusted bleach call), never on unwashed user input.
• {% autoescape off %}: disables escaping for the entire block. Rarely needed, review every use.
• mark_safe(s) in Python code: same effect as |safe. If s contains user input or is composed of user input, you have XSS.
• format_html('<a href="{}">', user_url): URL attributes are a separate problem. javascript: URLs via href bypass HTML escaping. Validate user_url.startswith(('http:', 'https:')).
• Server-side template injection: if you render templates yourself with user-controlled template strings (Template(user_input).render(...)), you get SSTI with potential RCE. Never do this.
• HttpResponse(user_input): bypasses template autoescape because there is no template. Use render() or encode explicitly.

4. CSRF model

Django's CsrfViewMiddleware is on by default for POST/PUT/PATCH/DELETE.

• @csrf_exempt: turns CSRF off for a specific view. Use only on endpoints where CSRF structurally cannot work (e.g. webhook receivers with signature verification). Every @csrf_exempt in a PR is a security-review moment.
• DRF and CSRF: DRF SessionAuthentication enforces CSRF, TokenAuthentication/JWT does not (stateless). Mixed auth modes: be explicit about which endpoints use which model.
• CSRF_COOKIE_HTTPONLY: default False, which is needed for JS to read the token. Do not change unless you have a custom CSRF setup.
• CSRF_TRUSTED_ORIGINS: stricter interpretation since Django 4 (full origin with scheme). Without correct config: legitimate POSTs are 403-rejected.

5. Auth, session, and admin

• django.contrib.auth.password_validation: never remove. Length check, common-password check, attribute-similarity check must be active.
• AUTHENTICATION_BACKENDS: custom backends are a classic foot-gun. Every custom backend must be timing-safe (identical response time for "user does not exist" vs. "wrong password").
• Admin interface:
  • ADMIN_URL not /admin/ (security through obscurity + bot-traffic reduction).
  • IP allowlist via middleware or reverse proxy for /admin/*.
  • 2FA required via django-otp or django-allauth with TOTP.
  • is_staff and is_superuser assigned carefully. Superuser status only for a small team.
• Session management: SESSION_COOKIE_AGE reasonably short, SESSION_EXPIRE_AT_BROWSER_CLOSE where appropriate, session rotation on privilege change (automatic on login since Django 2+).
• django-allauth/django-axes for rate-limiting on login (brute-force prevention). Native Django has no rate limiter on auth endpoints.

6. Misc and verification-loop

• File uploads: FileField does not validate content type. UploadedFile.content_type is set by the client. Validate magic bytes, whitelist extensions, store outside web root.
• Open redirects: redirect(request.GET.get('next')) without validation is an open redirect. Django has url_has_allowed_host_and_scheme(url, allowed_hosts=...) for this purpose.
• Middleware order: SecurityMiddleware belongs high, CsrfViewMiddleware before AuthenticationMiddleware, custom middleware with side effects close to the view. Wrong order can produce subtle bypasses.
• django-admin check with --deploy required in CI.
• Bandit + Semgrep p/django as the SAST layer, see sast-orchestrator.

Verification-loop: Layer 1 scope (settings file + urls + middleware stack all walked through?), assumptions (autoescape on everywhere, no |safe on user input?), gaps (DRF views included in the same review?). Layer 2 specifically on CVE IDs (verify against Django release notes, not memory), security-setting names (Django sometimes changes default values per major version), admin-hardening claims backed by concrete middleware/package.

Output

Follow the security-review report format, with a Django-specific scan summary at the top:

Django security review — <app/project>
Django version: <x.y.z> (latest security release: <...>)

Deploy checklist (python manage.py check --deploy):
  Warnings: N → resolved/open
  DEBUG in prod:        <False | FINDING>
  ALLOWED_HOSTS:        <explicit | wildcard — FINDING>
  SECURE_* settings:    <complete | gaps>
  PASSWORD_HASHERS:     <Argon2 first | PBKDF2 default>

Code patterns:
  @csrf_exempt:         <N, location, reason>
  |safe / mark_safe:    <N, on user input? FINDING>
  .raw() / .extra():    <N, parameterized?>
  order_by(user input): <list>

Admin:
  URL not /admin/:      <yes/no>
  IP restriction:       <yes/no>
  2FA on staff:         <yes/no>

Version check:
  On latest security release: <yes | N months behind>
  CVE relevance:              <handoff to cve-triage>

Findings (severity-sorted, follow security-review format)
Verification-loop: ...

References

• Django Security — https://docs.djangoproject.com/en/stable/topics/security/. Official security topic page.
• Django Deployment Checklist — https://docs.djangoproject.com/en/stable/howto/deployment/checklist/. Exactly what manage.py check --deploy checks.
• Django Security Releases — https://docs.djangoproject.com/en/dev/releases/security/. Canonical CVE log per version.
• Django Admin Security — https://docs.djangoproject.com/en/stable/ref/contrib/admin/#adminsite-objects. Admin configuration reference.
• OWASP Django Security Cheat Sheet — https://cheatsheetseries.owasp.org/cheatsheets/Django_Security_Cheat_Sheet.html.
• Django Rest Framework — Authentication — https://www.django-rest-framework.org/api-guide/authentication/. DRF auth-mode matrix.
• django-axes — https://django-axes.readthedocs.io/. Login-attempt rate-limiting.
• django-otp — https://django-otp-official.readthedocs.io/. 2FA on admin.

Categories

• appsec