djangorestframework: Django REST framework: TokenProxy.delete() reports success and revokes nothing

Summary

Deleting an authentication token through TokenProxy silently deletes nothing. The call raises no exception and reports success, the database row survives, and the token keeps authenticating. Any application, admin integration or operational script that revokes credentials by calling .delete() on a TokenProxy instance believes it has revoked a token that is still live.

Details

TokenProxy overrides pk to return the user id (rest_framework/authtoken/models.py:49-63):

@property
def pk(self):
    return self.user_id

The concrete Token model keys on key, not on an integer id. Model.delete() builds its delete query from pk, so it emits:

DELETE FROM "authtoken_token" WHERE "authtoken_token"."key" IN ('1')

That matches a user id against the 40-character key column. Nothing matches, nothing raises, and the call returns (0, {'authtoken.TokenProxy': 0}).

DRF already ships two workarounds for this same identity mismatch instead of a fix. In rest_framework/authtoken/admin.py, TokenAdmin.delete_model re-fetches the concrete row:

def delete_model(self, request, obj):
    Token.objects.get(key=obj.key).delete()   # admin.py:30

and TokenAdmin sets actions = None with the comment "Actions not compatible with mapped IDs" (admin.py:50-53). The shipped admin path is therefore safe, and every other caller of TokenProxy.delete() is not. Nothing in the API signals the difference.

TokenProxy was added by e2bd3b6a (PR #7341, "Adjusted token admin to map to user ID"), first released in 3.12.0.

A fix would drop the pk override, or give TokenProxy a delete() that operates on the concrete row, or raise instead of silently reporting zero deletions.

PoC

Save as poc_tokenproxy_revocation.py and run it.

#!/usr/bin/env python
"""
django-rest-framework: TokenProxy.delete() reports success and revokes nothing.

  baseline  token exists                        -> 200
  TRIGGER   TokenProxy.objects.get(...).delete() -> no exception, row survives, still 200
  CONTROL   Token.objects.get(key=...).delete()  -> row gone, 401

The control is what makes the trigger meaningful: it proves the row was
deletable and the credential check live, so the 200 after the proxy delete is a
failed revocation and not a broken harness.

Requires: django, djangorestframework importable. No arguments.
    python poc_tokenproxy_revocation.py
Exit status 0 means the revocation failure reproduced.
"""
import sys

import django
from django.conf import settings

settings.configure(
    DEBUG=False,
    SECRET_KEY="poc",
    ALLOWED_HOSTS=["*"],
    ROOT_URLCONF=__name__,
    INSTALLED_APPS=[
        "django.contrib.contenttypes",
        "django.contrib.auth",
        "rest_framework",
        "rest_framework.authtoken",
    ],
    DATABASES={"default": {"ENGINE": "django.db.backends.sqlite3", "NAME": ":memory:"}},
    DEFAULT_AUTO_FIELD="django.db.models.AutoField",
    USE_TZ=True,
)
django.setup()

from django.contrib.auth import get_user_model  # noqa: E402
from django.core.management import call_command  # noqa: E402
from django.db import connection  # noqa: E402
from django.test import Client  # noqa: E402
from django.test.utils import CaptureQueriesContext  # noqa: E402
from django.urls import path  # noqa: E402

from rest_framework.authentication import TokenAuthentication  # noqa: E402
from rest_framework.authtoken.models import Token, TokenProxy  # noqa: E402
from rest_framework.permissions import IsAuthenticated  # noqa: E402
from rest_framework.response import Response  # noqa: E402
from rest_framework.views import APIView  # noqa: E402


class Whoami(APIView):
    authentication_classes = [TokenAuthentication]
    permission_classes = [IsAuthenticated]

    def get(self, request):
        return Response({"user": request.user.get_username()})


urlpatterns = [path("", Whoami.as_view())]


def probe(client, key):
    response = client.get("/", headers={"authorization": "Token %s" % key})
    return response.status_code


def main():
    call_command("migrate", run_syncdb=True, verbosity=0)
    user = get_user_model().objects.create_user(username="revoke-user", password="pw")
    key = Token.objects.create(user=user).key
    client = Client()

    print("TokenProxy._meta.proxy   =", TokenProxy._meta.proxy)
    print("Token._meta.pk.attname   =", Token._meta.pk.attname)
    print("user.pk                  =", user.pk)
    print("token key                =", key)

    print("\n--- baseline")
    print("rows                     =", Token.objects.count())
    baseline = probe(client, key)
    print("GET / with token         ->", baseline)

    print("\n--- TRIGGER: delete through the proxy")
    proxy = TokenProxy.objects.get(user=user)
    print("proxy.pk                 =", proxy.pk, "(TokenProxy.pk property)")
    raised = None
    with CaptureQueriesContext(connection) as ctx:
        try:
            returned = proxy.delete()
        except Exception as exc:  # noqa: BLE001
            raised, returned = exc, None
    for q in ctx.captured_queries:
        if "DELETE" in q["sql"]:
            print("    SQL:", q["sql"])
    print("raised                   =", repr(raised))
    print("returned                 =", returned)
    print("rows                     =", Token.objects.count())
    after_proxy = probe(client, key)
    print("GET / with token         ->", after_proxy)

    print("\n--- CONTROL: delete the same row through the concrete model")
    with CaptureQueriesContext(connection) as ctx2:
        returned2 = Token.objects.get(key=key).delete()
    for q in ctx2.captured_queries:
        if "DELETE" in q["sql"]:
            print("    SQL:", q["sql"])
    print("returned                 =", returned2)
    print("rows                     =", Token.objects.count())
    after_real = probe(client, key)
    print("GET / with token         ->", after_real)

    ok = baseline == 200 and raised is None and after_proxy == 200 and after_real == 401
    print(
        "\nrevocation failure reproduced:", ok,
        "(baseline 200, still 200 after proxy delete, 401 after real delete)",
    )
    return 0 if ok else 1


if __name__ == "__main__":
    sys.exit(main())

Observed output:

TokenProxy._meta.proxy   = True
Token._meta.pk.attname   = key
user.pk                  = 1
token key                = 6a644878f252175d39205804c5a6faf16df67c10

--- baseline
rows                     = 1
GET / with token         -> 200

--- TRIGGER: delete through the proxy
proxy.pk                 = 1 (TokenProxy.pk property)
    SQL: DELETE FROM "authtoken_token" WHERE "authtoken_token"."key" IN ('1')
raised                   = None
returned                 = (0, {'authtoken.TokenProxy': 0})
rows                     = 1
GET / with token         -> 200

--- CONTROL: delete the same row through the concrete model
    SQL: DELETE FROM "authtoken_token" WHERE "authtoken_token"."key" IN ('6a644878...')
returned                 = (1, {'authtoken.Token': 1})
rows                     = 0
GET / with token         -> 401

revocation failure reproduced: True

The control is what makes the trigger meaningful: it proves the row was deletable and the credential check live, so the 200 after the proxy delete is a failed revocation and not a broken harness. Reproduced identically on Django 6.1 and 5.2.17 LTS, so this is not a recent Django regression.

Impact

Failed credential revocation. An operator who revokes a token through a TokenProxy instance, and receives no error, leaves a live credential in circulation indefinitely, because DRF auth tokens do not expire on their own. Whoever holds that token benefits: a departed employee, a rotated integration, a device believed to be deprovisioned, or an attacker whose access was thought to have been cut during incident response.

No untrusted input reaches this code path, which is why the vector is scored AC:H. Exploitation depends on the deployment revoking through the proxy, which is a natural thing to do given TokenProxy is the model registered in the admin and the one most code will reach for. Any deployment on 3.12.0 or later that revokes tokens outside DRF's own TokenAdmin.delete_model should audit whether its revocations took effect.