[WEB-8374] fix(security): scope ProjectMemberPreferenceEndpoint to the caller (GHSA-gx67-r6wp-3357)

ProjectMemberPreferenceEndpoint.get/patch took a member_id URL param and loaded
the ProjectMember by (project_id, member_id, workspace__slug) with no check that
member_id is the requesting user. Any project member (including a Guest) could
read and modify any other member's per-project preferences by supplying their
member_id.

Preferences are personal — reject any request where member_id != request.user.id
with 403, on both get and patch.

Adds 4 contract tests (cross-member read/write blocked, own read/write allowed);
fail-before verified.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

apps/api/plane/app/views/project/member.py

@@ -389,6 +389,14 @@ class ProjectMemberPreferenceEndpoint(BaseAPIView):
 
     @allow_permission([ROLE.ADMIN, ROLE.MEMBER, ROLE.GUEST])
     def patch(self, request, slug, project_id, member_id):
+        # Preferences are personal: a member may only read/modify their OWN
+        # preferences. member_id is a URL param, so reject any mismatch to prevent
+        # cross-member IDOR (GHSA-gx67-r6wp-3357).
+        if str(member_id) != str(request.user.id):
+            return Response(
+                {"error": "You cannot access another member's preferences."},
+                status=status.HTTP_403_FORBIDDEN,
+            )
         project_member = self.get_queryset(slug, project_id, member_id)
 
         serializer = ProjectMemberPreferenceSerializer(project_member, {"preferences": request.data}, partial=True)
@@ -401,6 +409,13 @@ class ProjectMemberPreferenceEndpoint(BaseAPIView):
 
     @allow_permission([ROLE.ADMIN, ROLE.MEMBER, ROLE.GUEST])
     def get(self, request, slug, project_id, member_id):
+        # Preferences are personal: a member may only read their OWN preferences.
+        # member_id is a URL param, so reject any mismatch (GHSA-gx67-r6wp-3357).
+        if str(member_id) != str(request.user.id):
+            return Response(
+                {"error": "You cannot access another member's preferences."},
+                status=status.HTTP_403_FORBIDDEN,
+            )
         project_member = self.get_queryset(slug, project_id, member_id)
 
         serializer = ProjectMemberPreferenceSerializer(project_member)

apps/api/plane/tests/contract/app/test_member_preference_scope_app.py

@@ -0,0 +1,102 @@
+# Copyright (c) 2023-present Plane Software, Inc. and contributors
+# SPDX-License-Identifier: AGPL-3.0-only
+# See the LICENSE file for details.
+
+"""Contract tests for ProjectMemberPreferenceEndpoint ownership scoping.
+
+Regression coverage for GHSA-gx67-r6wp-3357. The endpoint takes a ``member_id``
+URL parameter and loaded the ``ProjectMember`` by ``(project_id, member_id,
+workspace__slug)`` with no check that ``member_id`` is the caller — so any project
+member (including a Guest) could read and modify any other member's per-project
+preferences.
+
+The fix rejects any request where ``member_id != request.user.id`` (403);
+preferences are personal.
+"""
+
+from uuid import uuid4
+
+import pytest
+from rest_framework import status
+from rest_framework.test import APIClient
+
+from plane.db.models import Project, ProjectMember, User, WorkspaceMember
+
+PREF_URL = "/api/workspaces/{slug}/projects/{project_id}/preferences/member/{member_id}/"
+
+
+def _member(workspace, project, *, role):
+    unique = uuid4().hex[:8]
+    user = User.objects.create(email=f"pref-{role}-{unique}@plane.so", username=f"pref_{role}_{unique}")
+    user.set_password("test-password")
+    user.save()
+    WorkspaceMember.objects.create(workspace=workspace, member=user, role=role, is_active=True)
+    ProjectMember.objects.create(project=project, member=user, workspace=workspace, role=role, is_active=True)
+    return user
+
+
+def _client(user):
+    client = APIClient()
+    client.force_authenticate(user=user)
+    return client
+
+
+@pytest.fixture
+def project(db, workspace, create_user):
+    project = Project.objects.create(
+        name="Pref Project", identifier="PR", workspace=workspace, created_by=create_user
+    )
+    ProjectMember.objects.create(project=project, member=create_user, workspace=workspace, role=20, is_active=True)
+    return project
+
+
+@pytest.mark.contract
+@pytest.mark.django_db
+class TestMemberPreferenceScope:
+    """A member may only read/modify their OWN project preferences."""
+
+    def test_member_cannot_read_others_preferences(self, workspace, project, create_user):
+        attacker = _member(workspace, project, role=15)
+        # attacker requests the admin (create_user)'s preferences
+        response = _client(attacker).get(
+            PREF_URL.format(slug=workspace.slug, project_id=project.id, member_id=create_user.id)
+        )
+        assert response.status_code == status.HTTP_403_FORBIDDEN, (
+            f"Got {response.status_code}: {getattr(response, 'data', None)!r}"
+        )
+
+    def test_member_cannot_modify_others_preferences(self, workspace, project, create_user):
+        attacker = _member(workspace, project, role=15)
+        victim_member = ProjectMember.objects.get(project=project, member=create_user)
+        original = victim_member.preferences
+
+        response = _client(attacker).patch(
+            PREF_URL.format(slug=workspace.slug, project_id=project.id, member_id=create_user.id),
+            {"pinned": ["hacked"]},
+            format="json",
+        )
+        assert response.status_code == status.HTTP_403_FORBIDDEN, (
+            f"Got {response.status_code}: {getattr(response, 'data', None)!r}"
+        )
+        victim_member.refresh_from_db()
+        assert victim_member.preferences == original, "Another member's preferences were modified"
+
+    def test_member_can_read_own_preferences(self, workspace, project):
+        member = _member(workspace, project, role=15)
+        response = _client(member).get(
+            PREF_URL.format(slug=workspace.slug, project_id=project.id, member_id=member.id)
+        )
+        assert response.status_code == status.HTTP_200_OK, (
+            f"Got {response.status_code}: {getattr(response, 'data', None)!r}"
+        )
+
+    def test_member_can_modify_own_preferences(self, workspace, project):
+        member = _member(workspace, project, role=15)
+        response = _client(member).patch(
+            PREF_URL.format(slug=workspace.slug, project_id=project.id, member_id=member.id),
+            {"pinned": ["my-view"]},
+            format="json",
+        )
+        assert response.status_code == status.HTTP_200_OK, (
+            f"Got {response.status_code}: {getattr(response, 'data', None)!r}"
+        )