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A cross-site request forgery (CSRF) attack occurs when a trusted user of a web application can be forced, by an attacker, to perform sensitive
actions that he didn’t intend, such as updating his profile or sending a message, more generally anything that can change the state of the
application.
The attacker can trick the user/victim to click on a link, corresponding to the privileged action, or to visit a malicious web site that embeds a
hidden web request and as web browsers automatically include cookies, the actions can be authenticated and sensitive.
Ask Yourself Whether

   The web application uses cookies to authenticate users. 
   There exist sensitive operations in the web application that can be performed when the user is authenticated. 
   The state / resources of the web application can be modified by doing HTTP POST or HTTP DELETE requests for example. 

There is a risk if you answered yes to any of those questions.
Recommended Secure Coding Practices

   Protection against CSRF attacks is strongly recommended:
    
       to be activated by default for all unsafe HTTP
      methods. 
       implemented, for example, with an unguessable CSRF token 
    
  
   Of course all sensitive operations should not be performed with safe HTTP methods like GET which are designed to be
  used only for information retrieval. 

Sensitive Code Example
For a Django application, the code is sensitive when,

   django.middleware.csrf.CsrfViewMiddleware is not used in the Django settings: 

MIDDLEWARE = [
    'django.middleware.security.SecurityMiddleware',
    'django.contrib.sessions.middleware.SessionMiddleware',
    'django.middleware.common.CommonMiddleware',
    'django.contrib.auth.middleware.AuthenticationMiddleware',
    'django.contrib.messages.middleware.MessageMiddleware',
    'django.middleware.clickjacking.XFrameOptionsMiddleware',
] # Sensitive: django.middleware.csrf.CsrfViewMiddleware is missing


   the CSRF protection is disabled on a view: 

@csrf_exempt # Sensitive
def example(request):
    return HttpResponse("default")

For a Flask application, the code is sensitive when,

   the WTF_CSRF_ENABLED setting is set to false: 

app = Flask(__name__)
app.config['WTF_CSRF_ENABLED'] = False # Sensitive


   the application doesn’t use the CSRFProtect module: 

app = Flask(__name__) # Sensitive: CSRFProtect is missing

@app.route('/')
def hello_world():
    return 'Hello, World!'


   the CSRF protection is disabled on a view: 

app = Flask(__name__)
csrf = CSRFProtect()
csrf.init_app(app)

@app.route('/example/', methods=['POST'])
@csrf.exempt # Sensitive
def example():
    return 'example '


   the CSRF protection is disabled on a form: 

class unprotectedForm(FlaskForm):
    class Meta:
        csrf = False # Sensitive

    name = TextField('name')
    submit = SubmitField('submit')

Compliant Solution
For a Django application,

   it is recommended to protect all the views with django.middleware.csrf.CsrfViewMiddleware: 

MIDDLEWARE = [
    'django.middleware.security.SecurityMiddleware',
    'django.contrib.sessions.middleware.SessionMiddleware',
    'django.middleware.common.CommonMiddleware',
    'django.middleware.csrf.CsrfViewMiddleware', # Compliant
    'django.contrib.auth.middleware.AuthenticationMiddleware',
    'django.contrib.messages.middleware.MessageMiddleware',
    'django.middleware.clickjacking.XFrameOptionsMiddleware',
]


   and to not disable the CSRF protection on specific views: 

def example(request): # Compliant
    return HttpResponse("default")

For a Flask application,

   the CSRFProtect module should be used (and not disabled further with WTF_CSRF_ENABLED set to false):
  

app = Flask(__name__)
csrf = CSRFProtect()
csrf.init_app(app) # Compliant


   and it is recommended to not disable the CSRF protection on specific views or forms: 

@app.route('/example/', methods=['POST']) # Compliant
def example():
    return 'example '

class unprotectedForm(FlaskForm):
    class Meta:
        csrf = True # Compliant

    name = TextField('name')
    submit = SubmitField('submit')

See

   OWASP - Top 10 2021 Category A1 - Broken Access Control 
   CWE - CWE-352 - Cross-Site Request Forgery (CSRF) 
   OWASP - Top 10 2017 Category A6 - Security
  Misconfiguration 
   OWASP - Cross-Site Request Forgery 
   STIG Viewer - Application Security and
  Development: V-222603 - The application must protect from Cross-Site Request Forgery (CSRF) vulnerabilities. 
   PortSwigger - Web storage: the lesser evil for
  session tokens