Sensitive cookie with SameSite attribute set to None — CodeQL query help documentation
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Sensitive cookie with SameSite attribute set to None
ID: py/samesite-none-cookie
Kind: problem
Security severity: 4.0
Severity: warning
Precision: high
Tags:
- security
- external/cwe/cwe-1275
Query suites:
- python-code-scanning.qls
- python-security-extended.qls
- python-security-and-quality.qls
Click to see the query in the CodeQL repository
Cookies with the SameSite attribute set to 'None' will be sent with cross-origin requests. This can sometimes allow for Cross-Site Request Forgery (CSRF) attacks, in which a third-party site could perform actions on behalf of a user, if the cookie is used for authentication.
Recommendation
Set the samesite to Lax or Strict, or add ; SameSite=Lax;, or ; SameSite=Strict; to the cookie’s raw header value. The default value in most cases is Lax.
Example
In the following examples, the cases marked GOOD show secure cookie attributes being set; whereas in the case marked BAD they are not set.
from flask import Flask, request, make_response, Response
@app.route("/good1")
def good1():
resp = make_response()
resp.set_cookie("sessionid", value="value", secure=True, httponly=True, samesite='Strict') # GOOD: Attributes are securely set
return resp
@app.route("/good2")
def good2():
resp = make_response()
resp.headers['Set-Cookie'] = "sessionid=value; Secure; HttpOnly; SameSite=Strict" # GOOD: Attributes are securely set
return resp
@app.route("/bad1")
def bad1():
resp = make_response()
resp.set_cookie("sessionid", value="value", samesite='None') # BAD: the SameSite attribute is set to 'None' and the 'Secure' and 'HttpOnly' attributes are set to False by default.
return resp
References