fix(credentials): deny non-admin patches that would widen an auto-enabled destination

An auto_enable destination with no explicit grants falls back to proxy-wide
visibility, so a team-admin emptying the last team grant turned a
team-scoped destination into one receiving every tenant's traces. The
decider now refuses a non-admin patch when the post-merge access would
have no grant left on an auto_enable destination; revoking with a
surviving org or global grant, revoking on manual destinations, and
proxy-admin edits are unchanged. The deny reason is safe to surface
because the path is only reachable by a caller whose own teams hold every
grant being removed, so the destination is already visible to them

litellm/proxy/credential_endpoints/access_decision.py

@@ -70,7 +70,8 @@ def decide_credential_patch(
     modify any immutable ``credential_info`` field, and (c) limits its
     ``access`` change to appending team_ids the caller is team-admin of to
     ``access.teams`` (no removals, no foreign ids, no ``global``/``orgs``
-    edits).
+    edits), and (d) does not remove the last explicit grant from an
+    ``auto_enable`` destination, whose empty-grant fallback is proxy-wide.
     """
     if is_proxy_admin:
         return Allow()
@@ -129,4 +130,14 @@ def decide_credential_patch(
             from_user_input=True,
         )
 
+    auto_enable = existing_info.auto_enable if existing_info is not None else False
+    had_explicit_grants = bool(existing_global or existing_teams or existing_orgs)
+    grants_after_merge = bool(existing_global or existing_orgs or patch_teams)
+    if auto_enable and had_explicit_grants and not grants_after_merge:
+        return Deny(
+            "removing the last grant would make this auto-enabled destination "
+            "proxy-wide; only the proxy admin can remove it",
+            from_user_input=True,
+        )
+
     return Allow()

tests/test_litellm/proxy/credential_endpoints/test_access_decision.py

@@ -293,6 +293,63 @@ class TestTeamAdminRevoke:
         assert "team-B" not in d.reason
 
 
+class TestAutoEnableWideningGuard:
+    """Emptying the last grant of an auto_enable destination falls through to
+    the documented empty-grants-means-proxy-wide fallback, so a narrowing edit
+    by a team-admin would widen the destination to every tenant. The decider
+    must refuse to cross that boundary for non-admins."""
+
+    def test_emptying_sole_grant_on_auto_enable_destination_is_denied(self):
+        existing = {
+            **_EXISTING_INFO,
+            "auto_enable": True,
+            "access": {"global": False, "teams": ["team-T"], "orgs": []},
+        }
+        d = _decision(
+            existing_info=existing,
+            patch_info={"access": {"teams": []}},
+        )
+        assert isinstance(d, Deny)
+        assert "proxy-wide" in d.reason
+
+    def test_emptying_teams_with_surviving_org_grant_is_allowed(self):
+        existing = {
+            **_EXISTING_INFO,
+            "auto_enable": True,
+            "access": {"global": False, "teams": ["team-T"], "orgs": ["org-1"]},
+        }
+        d = _decision(
+            existing_info=existing,
+            patch_info={"access": {"teams": []}},
+        )
+        assert isinstance(d, Allow)
+
+    def test_emptying_sole_grant_without_auto_enable_is_allowed(self):
+        existing = {
+            **_EXISTING_INFO,
+            "auto_enable": False,
+            "access": {"global": False, "teams": ["team-T"], "orgs": []},
+        }
+        d = _decision(
+            existing_info=existing,
+            patch_info={"access": {"teams": []}},
+        )
+        assert isinstance(d, Allow)
+
+    def test_proxy_admin_may_empty_sole_grant_on_auto_enable_destination(self):
+        existing = {
+            **_EXISTING_INFO,
+            "auto_enable": True,
+            "access": {"global": False, "teams": ["team-T"], "orgs": []},
+        }
+        d = _decision(
+            is_proxy_admin=True,
+            existing_info=existing,
+            patch_info={"access": {"teams": []}},
+        )
+        assert isinstance(d, Allow)
+
+
 class TestTeamAdminMultipleTeams:
     def test_can_add_multiple_own_team_ids(self):
         d = _decision(