CVE-2025-21815
📋 TL;DR
A Linux kernel memory management vulnerability where improper bounds checking in the compaction subsystem could allow shift-out-of-bounds operations. This affects all Linux systems running vulnerable kernel versions, potentially leading to kernel crashes or instability.
💻 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 →⚠️ Risk & Real-World Impact
Worst Case
Kernel panic leading to system crash and denial of service, potentially allowing limited information disclosure through crash dumps.
Likely Case
System instability or kernel crash requiring reboot, causing temporary denial of service.
If Mitigated
Minimal impact with proper kernel hardening and isolation controls in place.
🎯 Exploit Status
Requires ability to trigger specific memory compaction operations; discovered via syzkaller fuzzing.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Patches available in stable kernel branches via provided git commits
Vendor Advisory: https://git.kernel.org/stable/c/10b7d3eb535098ccd4c82a182a33655d8a0e5c88
Restart Required: Yes
Instructions:
1. Update Linux kernel to patched version from distribution vendor. 2. Rebuild kernel if using custom build. 3. Reboot system to load new kernel.
🔧 Temporary Workarounds
Disable memory compaction
allTemporarily disable kernel memory compaction feature to prevent triggering vulnerability
echo 0 > /proc/sys/vm/compact_memory
sysctl -w vm.compact_memory=0
🧯 If You Can't Patch
- Implement strict access controls to limit local user privileges
- Monitor system logs for kernel panic or OOPS messages indicating exploitation attempts
🔍 How to Verify
Check if Vulnerable:
Check kernel version and compare against patched versions from distribution vendorCheck Version:
uname -rVerify Fix Applied:
Verify kernel version after update matches patched version from vendor📡 Detection & Monitoring
Log Indicators:
- Kernel OOPS messages
- UBSAN warnings in dmesg
- System crash/panic logs
Network Indicators:
- None - local vulnerability only
SIEM Query:
Search for 'UBSAN shift-out-of-bounds' or 'kernel panic' in system logs