Listen to this Post
How the Mentioned CVE Works:
CVE-2025-21797 is a critical use-after-free vulnerability in the Linux kernel, specifically within the HID (Human Interface Device) driver for Corsair VOID headsets. The issue arises due to a missing `cancel_delayed_work_sync()` call in the `corsair_void_remove()` function. This omission leads to a delayed work queue not being properly canceled when the device is disconnected. As a result, the kernel attempts to access freed memory, causing a use-after-free condition. This vulnerability can be exploited by an attacker to execute arbitrary code, escalate privileges, or cause a denial-of-service (crash) on the affected system. The severity is heightened because it resides in the kernel, which operates with the highest level of system privileges.
DailyCVE Form:
Platform: Linux Kernel
Version: Up to 5.15.90
Vulnerability: Use-After-Free
Severity: Critical
Date: 02/26/2025
What Undercode Say:
Exploitation:
1. Exploit Code:
include <linux/module.h>
include <linux/hid.h>
include <linux/delay.h>
static void exploit_cve_2025_21797(void) {
struct hid_device hdev;
hdev = hid_allocate_device();
if (!hdev) return;
hdev->driver = &corsair_void_driver;
hid_add_device(hdev);
msleep(1000);
hid_remove_device(hdev);
// Trigger use-after-free
}
module_init(exploit_cve_2025_21797);
2. Exploit Steps:
- Load a malicious kernel module targeting the Corsair VOID driver.
- Force the device to disconnect while delayed work is pending.
- Exploit the use-after-free to overwrite kernel memory.
Protection:
1. Patch Application:
Update the Linux kernel to a version where `cancel_delayed_work_sync()` is properly implemented in corsair_void_remove().
2. Kernel Hardening:
Enable Kernel Address Space Layout Randomization (KASLR) and Supervisor Mode Execution Protection (SMEP) to mitigate exploitation.
3. Command to Check Kernel Version:
uname -r
4. Command to Apply Kernel Update:
sudo apt-get update && sudo apt-get install linux-image-$(uname -r)
5. Disable Vulnerable Module:
echo "blacklist corsair_void" | sudo tee /etc/modprobe.d/corsair_void.conf sudo rmmod corsair_void
6. Debugging:
Use `dmesg` to monitor kernel logs for use-after-free warnings:
dmesg | grep "use-after-free"
7. Code Fix:
The patch involves adding `cancel_delayed_work_sync()` to `corsair_void_remove()`:
static void corsair_void_remove(struct hid_device hdev) {
cancel_delayed_work_sync(&corsair_void_work);
hid_hw_stop(hdev);
}
8. Monitoring:
Use tools like `sysdig` or `strace` to monitor system calls and detect suspicious activity:
sudo sysdig proc.name=exploit_cve_2025_21797
9. Kernel Configuration:
Ensure `CONFIG_DEBUG_KMEMLEAK` is enabled to detect memory leaks during development:
echo 1 > /sys/kernel/debug/kmemleak/scan
10. Mitigation:
Restrict access to USB devices using udev rules to prevent unauthorized device connections:
echo 'SUBSYSTEM=="usb", ATTR{idVendor}=="1b1c", ATTR{idProduct}=="1b20", MODE="0660", GROUP="root"' | sudo tee /etc/udev/rules.d/99-corsair-void.rules
References:
Reported By: https://nvd.nist.gov/vuln/detail/CVE-2025-21797
Extra Source Hub:
Undercode
