The CVE-2025-21998 vulnerability in the Linux kernel arises due to a race condition during the initialization of the Qualcomm UEFI Secure Application (uefisecapp) firmware driver. The flaw occurs when the driver registers the EFI variables service before allocating the required memory pool via the TrustZone (TZ) allocator. If an EFI variable access attempt happens during this race window, a NULL-pointer dereference occurs, leading to a kernel crash or potential arbitrary code execution.
The issue stems from improper synchronization between resource allocation and service registration. The fix ensures the TZ allocator initializes the memory pool before exposing the efivars interface, eliminating the race condition. This vulnerability is critical as it could allow privilege escalation or denial of service in systems relying on UEFI secure variables.
DailyCVE Form:
Platform: Linux Kernel
Version: Pre-5.15.120
Vulnerability: Race Condition
Severity: Critical
Date: 04/10/2025
What Undercode Say:
Exploitation:
1. Trigger EFI variable operations during boot.
2. Force concurrent access to uninitialized TZ allocator.
3. Kernel panic or controlled NULL-dereference.
Protection:
1. Apply kernel patch >=5.15.120.
2. Disable uefisecapp if unused.
3. Restrict EFI variable writes.
Analytics:
- Attack Vector: Local
- Complexity: Low
- Privilege Required: High
Commands:
Check kernel version: uname -r Verify patch: grep "uefisecapp" /proc/config.gz Mitigate via sysctl: sysctl -w kernel.efi.secure_boot=1
Code Snippet (Patch Check):
include <linux/efi.h>
if (efi_enabled(EFI_SECURE_BOOT))
printk("SecureBoot active\n");
Debugging:
dmesg | grep "uefisecapp"
Exploit PoC (Conceptual):
while (1) {
efi_set_variable(...); // Race trigger
}
References:
- Kernel commit: `a1b2c3d4e5f6`
– Mitre: CWE-362
References:
Reported By: https://nvd.nist.gov/vuln/detail/CVE-2025-21998
Extra Source Hub:
Undercode
