CVE-2025-21729
📋 TL;DR
A race condition vulnerability in the Linux kernel's rtw89 WiFi driver allows a null pointer dereference and use-after-free when hardware scan cancellation and completion operations overlap. This can cause kernel crashes or potential privilege escalation. Systems using affected Realtek WiFi chipsets with vulnerable kernel versions are affected.
💻 Affected Systems
- Linux kernel with rtw89 WiFi driver
📦 What is this software?
Linux Kernel by Linux
The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...
Learn more about Linux Kernel →Linux Kernel by Linux
The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...
Learn more about Linux Kernel →⚠️ Risk & Real-World Impact
Worst Case
Kernel panic leading to system crash, potential privilege escalation to kernel mode, or arbitrary code execution in kernel context.
Likely Case
System instability, kernel crashes, or denial of service affecting WiFi functionality.
If Mitigated
Minor performance impact during WiFi scanning operations with proper mutex protection.
🎯 Exploit Status
Exploitation requires precise timing to trigger the race condition between scan cancellation and completion operations.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Kernel versions with commit 2403cb3c235d5e339b580cc3a825493769fadca8 or later
Vendor Advisory: https://git.kernel.org/stable/c/2403cb3c235d5e339b580cc3a825493769fadca8
Restart Required: No
Instructions:
1. Update Linux kernel to version containing the fix commit. 2. For distributions: Use package manager to update kernel package. 3. Rebuild kernel if using custom kernel with the fix applied.
🔧 Temporary Workarounds
Disable WiFi scanning
allPrevent WiFi scanning operations that trigger the vulnerable code path
# Disable WiFi scanning via network manager or manual configuration
# May impact WiFi roaming and network discovery
🧯 If You Can't Patch
- Restrict local user access to systems with vulnerable WiFi drivers
- Disable or remove rtw89 driver module if not required
🔍 How to Verify
Check if Vulnerable:
Check kernel version and if rtw89 module is loaded: lsmod | grep rtw89Check Version:
uname -rVerify Fix Applied:
Verify kernel version includes fix commit: git log --oneline | grep '2403cb3c235d5e339b580cc3a825493769fadca8'📡 Detection & Monitoring
Log Indicators:
- Kernel panic messages
- null pointer dereference errors in kernel logs
- rtw89_core module crash reports
Network Indicators:
- Unexpected WiFi disconnections
- Failed scan operations
SIEM Query:
source="kernel" AND ("null-ptr-deref" OR "rtw89" OR "scan_offload")