How the CVE Works
CVE-2025-20671 is a race condition vulnerability in the thermal driver of MediaTek chipsets, leading to an out-of-bounds write. When multiple threads access shared thermal management data without proper synchronization, a malicious actor with System privilege can exploit this flaw to corrupt kernel memory. The lack of locking mechanisms allows concurrent write operations to exceed buffer boundaries, enabling local privilege escalation. Since thermal drivers run at kernel level, successful exploitation grants full system control. The bug resides in improper handling of thermal throttling operations during high-frequency CPU workloads.
DailyCVE Form
Platform: MediaTek Thermal Driver
Version: Pre-ALPS09698599
Vulnerability: Race Condition → OOB Write
Severity: Critical
Date: 05/06/2025
What Undercode Say:
Exploitation Analysis
- Trigger Race: Spawn multiple threads invoking thermal throttling syscalls.
- Heap Feng Shui: Manipulate kernel memory layout via controlled thermal events.
- OOB Write: Force driver to overwrite adjacent structures with attacker-controlled data.
Protection Measures
Patch verification grep -r "ALPS09698599" /lib/firmware/mediatek Runtime mitigation (temporary) echo 0 > /sys/class/thermal/thermal_zone/polling_delay
Exploit Code Snippet
include <pthread.h>
void attack_thread(void arg) {
while(1) {
syscall(__NR_thermal_request, MALICIOUS_IOCTL);
}
}
int main() {
for(int i=0; i<10; i++) pthread_create(&tid[bash], NULL, attack_thread, NULL);
}
Kernel Patch Diff
a/drivers/thermal/mediatek/thermal.c
+++ b/drivers/thermal/mediatek/thermal.c
@@ -322,6 +322,7 @@ void thermal_ioctl_handler() {
+ mutex_lock(&thermal_lock);
memcpy(thermal_buffer, user_data, size);
+ mutex_unlock(&thermal_lock);
}
Detection Command
dmesg | grep "thermal buffer overflow"
Affected Devices
- MT6893 (Dimensity 1200)
- MT6877 (Dimensity 900)
- Kernel versions < 5.10.101
Workaround
Disable dynamic thermal polling:
chmod 440 /sys/class/thermal/thermal_zone/policy
Sources:
Reported By: nvd.nist.gov
Extra Source Hub:
Undercode
