CVE-2025-21966
📋 TL;DR
This vulnerability in the Linux kernel's dm-flakey device mapper target allows memory corruption due to incorrect parameter passing in the optional corrupt_bio_byte feature. Attackers could potentially exploit this to crash systems or execute arbitrary code. Systems using dm-flakey with the corrupt_bio_byte feature enabled are affected.
💻 Affected Systems
- Linux kernel
📦 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 →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 →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 →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 →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 memory corruption leading to system crash, privilege escalation, or arbitrary code execution with kernel privileges.
Likely Case
System instability, kernel panics, or denial of service affecting dm-flakey operations.
If Mitigated
Limited impact if dm-flakey is not used or corrupt_bio_byte feature is disabled.
🎯 Exploit Status
Exploitation requires access to configure dm-flakey devices and knowledge of the vulnerable feature.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Kernel versions containing commits 57e9417f69839cb10f7ffca684c38acd28ceb57b, 5a87e46da2418c57b445371f5ca0958d5779ba5f, 818330f756f3800c37d738bd36bce60eac949938, or da070843e153471be4297a12fdaa64023276f40e
Vendor Advisory: https://git.kernel.org/stable/c/57e9417f69839cb10f7ffca684c38acd28ceb57b
Restart Required: Yes
Instructions:
1. Update Linux kernel to patched version from your distribution's repositories. 2. Reboot system to load new kernel. 3. Verify kernel version after reboot.
🔧 Temporary Workarounds
Disable dm-flakey corrupt_bio_byte feature
linuxRemove or disable dm-flakey configurations using the corrupt_bio_byte parameter
dmsetup remove flakey-device-name
Remove corrupt_bio_byte parameter from dm-flakey table entries
🧯 If You Can't Patch
- Disable all dm-flakey device mapper targets if not required
- Restrict access to device mapper configuration to privileged users only
🔍 How to Verify
Check if Vulnerable:
Check if dm-flakey is in use: 'dmsetup table | grep flakey' and verify kernel version against patched commitsCheck Version:
uname -rVerify Fix Applied:
Check kernel version after update: 'uname -r' and verify it includes the fix commits📡 Detection & Monitoring
Log Indicators:
- Kernel oops messages
- System crashes related to dm-flakey
- Device mapper errors in dmesg
Network Indicators:
- None - this is a local kernel vulnerability
SIEM Query:
Search for: 'kernel: BUG:', 'kernel: Oops:', 'dm-flakey' in system logs