diff --git a/changes/16691-cross-team-user-list-teams-authz b/changes/16691-cross-team-user-list-teams-authz
new file mode 100644
index 00000000000..0ebb6e36070
--- /dev/null
+++ b/changes/16691-cross-team-user-list-teams-authz
@@ -0,0 +1 @@
+- Fixed fleet-scoped context when retrieving a list of users in a fleet. 
diff --git a/server/service/users.go b/server/service/users.go
index 51b38312daa..d54b3f66e8e 100644
--- a/server/service/users.go
+++ b/server/service/users.go
@@ -476,6 +476,22 @@ func listUsersEndpoint(ctx context.Context, request interface{}, svc fleet.Servi
 	return resp, nil
 }
 
+// filterUserTeamsToRequesterScope returns the subset of teams that the
+// requester is permitted to see. A requester with any global role sees all
+// teams unchanged; a team-scoped requester sees only teams they have a role in.
+func filterUserTeamsToRequesterScope(teams []fleet.UserTeam, requester *fleet.User) []fleet.UserTeam {
+	if requester.HasAnyGlobalRole() {
+		return teams
+	}
+	filtered := make([]fleet.UserTeam, 0, len(teams))
+	for _, t := range teams {
+		if requester.HasAnyRoleInTeam(t.ID) {
+			filtered = append(filtered, t)
+		}
+	}
+	return filtered
+}
+
 func (svc *Service) ListUsers(ctx context.Context, opt fleet.UserListOptions) ([]*fleet.User, error) {
 	user := &fleet.User{}
 	if opt.TeamID != 0 {
@@ -485,7 +501,26 @@ func (svc *Service) ListUsers(ctx context.Context, opt fleet.UserListOptions) ([
 		return nil, err
 	}
 
-	return svc.ds.ListUsers(ctx, opt)
+	vc, ok := viewer.FromContext(ctx)
+	if !ok {
+		return nil, fleet.ErrNoContext
+	}
+
+	users, err := svc.ds.ListUsers(ctx, opt)
+	if err != nil {
+		return nil, err
+	}
+
+	// The datastore loads each user's full team membership. A team-scoped
+	// requester is only authorized to list users of a team they administer, so
+	// strip any team memberships (IDs/names/roles) for teams the requester has
+	// no role in before returning them. Global roles are authorized to see all
+	// teams and are left untouched.
+	for _, user := range users {
+		user.Teams = filterUserTeamsToRequesterScope(user.Teams, vc.User)
+	}
+
+	return users, nil
 }
 
 func (svc *Service) UsersByIDs(ctx context.Context, ids []uint) ([]*fleet.UserSummary, error) {
diff --git a/server/service/users_test.go b/server/service/users_test.go
index 76bb14823d9..b81e90208fa 100644
--- a/server/service/users_test.go
+++ b/server/service/users_test.go
@@ -1907,3 +1907,74 @@ func TestPasswordChangeClearsTokensAndSessions(t *testing.T) {
 		assert.Equal(t, []uint{otherSession.ID}, destroyedSessionIDs, "should only destroy the other session, not the current one")
 	})
 }
+
+// TestListUsersFiltersTeamsToRequesterScope verifies that a team-scoped admin
+// listing users does not receive team memberships (IDs/names/roles) for teams
+// the requester has no role in. Regression test for the cross-team data
+// exposure on GET /api/latest/fleet/users for shared multi-team users.
+func TestListUsersFiltersTeamsToRequesterScope(t *testing.T) {
+	ds := new(mock.Store)
+	svc, ctx := newTestService(t, ds, nil, nil)
+
+	// A user shared across team 1 and team 2, as returned by the datastore
+	// (ds.ListUsers always loads the user's full team list).
+	sharedUserTeams := []fleet.UserTeam{
+		{Team: fleet.Team{ID: 1, Name: "Team 1"}, Role: fleet.RoleObserver},
+		{Team: fleet.Team{ID: 2, Name: "Team 2"}, Role: fleet.RoleObserver},
+	}
+	ds.ListUsersFunc = func(ctx context.Context, opt fleet.UserListOptions) ([]*fleet.User, error) {
+		return []*fleet.User{{
+			ID:    10,
+			Teams: append([]fleet.UserTeam{}, sharedUserTeams...),
+		}}, nil
+	}
+
+	// Requester is an admin of team 1 only, listing users of team 1.
+	teamOneAdmin := &fleet.User{
+		ID:    1,
+		Teams: []fleet.UserTeam{{Team: fleet.Team{ID: 1}, Role: fleet.RoleAdmin}},
+	}
+	ctx = viewer.NewContext(ctx, viewer.Viewer{User: teamOneAdmin})
+
+	resp, err := listUsersEndpoint(ctx, &listUsersRequest{
+		ListOptions: fleet.UserListOptions{TeamID: 1},
+	}, svc)
+	require.NoError(t, err)
+
+	lr, ok := resp.(listUsersResponse)
+	require.True(t, ok)
+	require.NoError(t, lr.Err)
+	require.Len(t, lr.Users, 1)
+
+	// The requester must only see team 1 (in scope), never team 2.
+	require.Len(t, lr.Users[0].Teams, 1)
+	require.Equal(t, uint(1), lr.Users[0].Teams[0].ID)
+}
+
+// TestListUsersGlobalRequesterSeesAllTeams verifies the filter does not strip
+// teams for a global-role requester, who is authorized to see all teams.
+func TestListUsersGlobalRequesterSeesAllTeams(t *testing.T) {
+	ds := new(mock.Store)
+	svc, ctx := newTestService(t, ds, nil, nil)
+
+	ds.ListUsersFunc = func(ctx context.Context, opt fleet.UserListOptions) ([]*fleet.User, error) {
+		return []*fleet.User{{
+			ID: 10,
+			Teams: []fleet.UserTeam{
+				{Team: fleet.Team{ID: 1, Name: "Team 1"}, Role: fleet.RoleObserver},
+				{Team: fleet.Team{ID: 2, Name: "Team 2"}, Role: fleet.RoleObserver},
+			},
+		}}, nil
+	}
+
+	ctx = viewer.NewContext(ctx, viewer.Viewer{User: test.UserAdmin})
+
+	resp, err := listUsersEndpoint(ctx, &listUsersRequest{}, svc)
+	require.NoError(t, err)
+
+	lr, ok := resp.(listUsersResponse)
+	require.True(t, ok)
+	require.NoError(t, lr.Err)
+	require.Len(t, lr.Users, 1)
+	require.Len(t, lr.Users[0].Teams, 2)
+}