diff --git a/src/plugin-qt/power/session/tests/CMakeLists.txt b/src/plugin-qt/power/session/tests/CMakeLists.txt
index 65c09ad5..1879f938 100644
--- a/src/plugin-qt/power/session/tests/CMakeLists.txt
+++ b/src/plugin-qt/power/session/tests/CMakeLists.txt
@@ -2,7 +2,7 @@
 # SPDX-License-Identifier: LGPL-3.0-or-later
 
 find_package(Qt6 REQUIRED COMPONENTS Test)
-find_program(DBUS_RUN_SESSION dbus-run-session REQUIRED)
+find_program(DBUS_DAEMON dbus-daemon REQUIRED)
 
 add_executable(tst-screensaverproxy
     tst-screensaverproxy.cpp
@@ -11,7 +11,12 @@ add_executable(tst-screensaverproxy
 )
 target_include_directories(tst-screensaverproxy PRIVATE ..)
 target_link_libraries(tst-screensaverproxy PRIVATE Qt6::Test Qt6::DBus Dtk6::Core)
+
+# run-with-private-bus.sh, not dbus-run-session: the usec LSM denies signals to
+# dbus-daemon, which would make dbus-run-session hang and the test time out.
 add_test(NAME power-screensaver-proxy
-    COMMAND ${DBUS_RUN_SESSION} --config-file=${CMAKE_CURRENT_SOURCE_DIR}/session.conf
-            -- $<TARGET_FILE:tst-screensaverproxy>)
-set_tests_properties(power-screensaver-proxy PROPERTIES TIMEOUT 20)
+    COMMAND ${CMAKE_CURRENT_SOURCE_DIR}/run-with-private-bus.sh
+            ${CMAKE_CURRENT_SOURCE_DIR}/session.conf
+            $<TARGET_FILE:tst-screensaverproxy>)
+set_tests_properties(power-screensaver-proxy PROPERTIES TIMEOUT 20
+    ENVIRONMENT "DBUS_DAEMON_BIN=${DBUS_DAEMON}")
diff --git a/src/plugin-qt/power/session/tests/run-with-private-bus.sh b/src/plugin-qt/power/session/tests/run-with-private-bus.sh
new file mode 100755
index 00000000..b7960a81
--- /dev/null
+++ b/src/plugin-qt/power/session/tests/run-with-private-bus.sh
@@ -0,0 +1,77 @@
+#!/bin/sh
+# SPDX-FileCopyrightText: 2026 UnionTech Software Technology Co., Ltd.
+#
+# SPDX-License-Identifier: LGPL-3.0-or-later
+#
+# Run a command against a freshly started private session bus.
+#
+# Do not use dbus-run-session here. It terminates the bus by signalling
+# dbus-daemon, and UOS kernels with the usec LSM label /usr/bin/dbus-daemon as
+# deepin_unkillable_t, so that signal is denied:
+#
+#   uavc: denied { signal } for comm="dbus-run-sessio"
+#         scontext=...:deepin_usec_t tcontext=...:deepin_unkillable_t
+#
+# dbus-run-session then waits forever for its daemon. That daemon also inherits
+# the stdout pipe of the test runner, so ctest never sees EOF and reports a
+# timeout even though the test itself finished and passed. Starting the daemon
+# with --fork avoids depending on a signal at all: cleanup below is best effort,
+# and an unreapable daemon only costs a little idle memory.
+#
+# Under fakeroot (dpkg-buildpackage) libfakeroot is injected through LD_PRELOAD
+# and fakes getuid() as root. The client then authenticates with "AUTH EXTERNAL
+# 30" while the daemon checks the real uid 10759 via SO_PEERCRED and refuses the
+# connection, so every registerObject/registerService call fails. The intercept
+# library is of no use to this test, so drop it and restore the real uid.
+LD_PRELOAD=
+export LD_PRELOAD
+
+set -u
+
+if [ $# -lt 2 ]; then
+    echo "usage: $0 <bus-config> <command> [args...]" >&2
+    exit 2
+fi
+
+bus_config=$1
+shift
+dbus_daemon=${DBUS_DAEMON_BIN:-dbus-daemon}
+
+command -v "$dbus_daemon" >/dev/null 2>&1 || {
+    echo "$0: dbus-daemon not found (looked for '$dbus_daemon')" >&2
+    exit 1
+}
+
+address_file=$(mktemp) || exit 1
+pid_file=$(mktemp) || exit 1
+trap 'rm -f "$address_file" "$pid_file"' EXIT HUP INT TERM
+
+# stdin and both output streams to /dev/null: a daemon that survives cleanup
+# must never hold a pipe of the test runner open.
+"$dbus_daemon" --config-file="$bus_config" --fork \
+    --print-address=3 --print-pid=4 \
+    3>"$address_file" 4>"$pid_file" </dev/null >/dev/null 2>&1 || {
+    echo "$0: cannot start $dbus_daemon with $bus_config" >&2
+    exit 1
+}
+
+bus_address=$(cat "$address_file")
+daemon_pid=$(cat "$pid_file")
+if [ -z "$bus_address" ]; then
+    echo "$0: dbus-daemon did not print a bus address" >&2
+    exit 1
+fi
+
+DBUS_SESSION_BUS_ADDRESS=$bus_address
+export DBUS_SESSION_BUS_ADDRESS
+
+"$@"
+status=$?
+
+# Best effort only: where the LSM allows it the daemon is reaped, where it does
+# not the failure to signal must not turn a passing test into a failing one.
+if [ -n "$daemon_pid" ]; then
+    kill "$daemon_pid" 2>/dev/null || :
+fi
+
+exit $status