diff --git a/litellm/proxy/management_endpoints/internal_user_endpoints.py b/litellm/proxy/management_endpoints/internal_user_endpoints.py
index 09cd7fc5f6..e343429ff1 100644
--- a/litellm/proxy/management_endpoints/internal_user_endpoints.py
+++ b/litellm/proxy/management_endpoints/internal_user_endpoints.py
@@ -1180,6 +1180,23 @@ async def _update_single_user_helper(
                     "error": "User does not have permission to update this user. Only PROXY_ADMIN can update other users."
                 },
             )
+    else:
+        # Silent-create guard: if the target user doesn't exist, the update
+        # path falls through to an upsert that creates a new user with
+        # caller-supplied fields (models, metadata, budgets, …). Only
+        # PROXY_ADMIN is allowed to create users this way; otherwise an org
+        # admin could spawn arbitrary users attached to nothing by supplying
+        # a fresh email, bypassing the /user/new org/team-scoping checks.
+        if user_api_key_dict.user_role != LitellmUserRoles.PROXY_ADMIN.value:
+            raise HTTPException(
+                status_code=404,
+                detail={
+                    "error": (
+                        "User not found. Only PROXY_ADMIN can create users "
+                        "via /user/update; use /user/new instead."
+                    )
+                },
+            )
 
     existing_metadata = (
         cast(Dict, getattr(existing_user_row, "metadata", {}) or {})
diff --git a/litellm/proxy/management_endpoints/team_endpoints.py b/litellm/proxy/management_endpoints/team_endpoints.py
index edd92cb83d..0bb6c3d90f 100644
--- a/litellm/proxy/management_endpoints/team_endpoints.py
+++ b/litellm/proxy/management_endpoints/team_endpoints.py
@@ -1544,6 +1544,42 @@ async def update_team(  # noqa: PLR0915
         if (
             data.organization_id is not None and len(data.organization_id) > 0
         ):  # allow unsetting the organization_id
+            # If the caller is relocating the team to a different org, they
+            # must also be PROXY_ADMIN or an org-admin of the DESTINATION org.
+            # _verify_team_access above only checked the team's CURRENT org,
+            # so without this gate an org-admin could hand their team to any
+            # other org (or capture a team from another org they once
+            # administered into a new destination).
+            current_org_id = getattr(existing_team_row, "organization_id", None)
+            if (
+                data.organization_id != current_org_id
+                and user_api_key_dict.user_role
+                != LitellmUserRoles.PROXY_ADMIN.value
+            ):
+                # Is the caller org_admin of the destination org?
+                caller_memberships = (
+                    await prisma_client.db.litellm_organizationmembership.find_many(
+                        where={
+                            "user_id": user_api_key_dict.user_id,
+                            "organization_id": data.organization_id,
+                            "user_role": LitellmUserRoles.ORG_ADMIN.value,
+                        }
+                    )
+                    if user_api_key_dict.user_id
+                    else []
+                )
+                if not caller_memberships:
+                    raise HTTPException(
+                        status_code=403,
+                        detail={
+                            "error": (
+                                "Relocating a team to a different organization "
+                                "requires PROXY_ADMIN or org-admin of the "
+                                "destination org."
+                            )
+                        },
+                    )
+
             await fetch_and_validate_organization(
                 organization_id=data.organization_id,
                 existing_team_row=existing_team_row,
@@ -2682,6 +2718,20 @@ async def bulk_team_member_add(
         )
 
     if data.all_users:
+        # `all_users=True` pulls every user in the database into this team,
+        # regardless of org. Any team admin could use it to capture every
+        # user across every org into a team they control. Restrict to
+        # PROXY_ADMIN.
+        if user_api_key_dict.user_role != LitellmUserRoles.PROXY_ADMIN.value:
+            raise HTTPException(
+                status_code=403,
+                detail={
+                    "error": (
+                        "`all_users=true` is restricted to PROXY_ADMIN. "
+                        "Org/team admins must specify explicit member lists."
+                    )
+                },
+            )
         # get all users from the database
         all_users_in_db = await prisma_client.db.litellm_usertable.find_many(
             order={"created_at": "desc"}
diff --git a/tests/test_litellm/proxy/management_endpoints/test_internal_user_endpoints.py b/tests/test_litellm/proxy/management_endpoints/test_internal_user_endpoints.py
index a074a4a211..a1ba7ecd67 100644
--- a/tests/test_litellm/proxy/management_endpoints/test_internal_user_endpoints.py
+++ b/tests/test_litellm/proxy/management_endpoints/test_internal_user_endpoints.py
@@ -1956,6 +1956,43 @@ async def test_delete_user_rejects_org_admin_deleting_outside_scope(mocker):
     ) == 0
 
 
+@pytest.mark.asyncio
+async def test_user_update_rejects_silent_create_for_non_proxy_admin(mocker):
+    """Regression: `/user/update` with an unknown user_email used to fall
+    through to an INSERT, silently creating a new user with caller-supplied
+    budget, models, and metadata. An org admin could use this to spawn
+    arbitrary users outside the /user/new authorization flow."""
+    from fastapi import HTTPException
+
+    from litellm.proxy._types import UpdateUserRequest, UserAPIKeyAuth
+    from litellm.proxy.management_endpoints.internal_user_endpoints import (
+        _update_single_user_helper,
+    )
+
+    mock_prisma_client = mocker.MagicMock()
+    # user_email lookup yields None → would silently create pre-fix.
+    mock_prisma_client.db.litellm_usertable.find_first = mocker.AsyncMock(
+        return_value=None
+    )
+    mocker.patch("litellm.proxy.proxy_server.prisma_client", mock_prisma_client)
+
+    user_request = UpdateUserRequest(
+        user_email="newcomer@example.com",
+        max_budget=1_000_000,
+        models=["gpt-4"],
+    )
+    org_admin = UserAPIKeyAuth(
+        user_id="org-admin",
+        user_role=LitellmUserRoles.ORG_ADMIN,
+    )
+
+    with pytest.raises(HTTPException) as exc:
+        await _update_single_user_helper(
+            user_request=user_request, user_api_key_dict=org_admin
+        )
+    assert exc.value.status_code == 404
+
+
 # =====================================================================
 # /v2/user/info endpoint tests
 # =====================================================================
diff --git a/tests/test_litellm/proxy/management_endpoints/test_team_endpoints.py b/tests/test_litellm/proxy/management_endpoints/test_team_endpoints.py
index 9b4bd79049..896e1efe0e 100644
--- a/tests/test_litellm/proxy/management_endpoints/test_team_endpoints.py
+++ b/tests/test_litellm/proxy/management_endpoints/test_team_endpoints.py
@@ -5128,6 +5128,16 @@ async def test_update_team_guardrails_with_org_id():
             return_value=mock_org
         )
 
+        # Destination-org guard in update_team queries for the caller's
+        # ORG_ADMIN membership on the destination org. Return a match so
+        # the guardrails-update path (the subject under test) proceeds.
+        mock_org_admin_membership = MagicMock()
+        mock_org_admin_membership.user_id = "org-admin-guardrails-test"
+        mock_org_admin_membership.organization_id = "test-org-guardrails"
+        mock_prisma.db.litellm_organizationmembership.find_many = AsyncMock(
+            return_value=[mock_org_admin_membership]
+        )
+
         # Mock team update
         mock_updated_team = MagicMock(spec=LiteLLM_TeamTable)
         mock_updated_team.team_id = "team-guardrails-123"