CVE-2024-56635
📋 TL;DR
A race condition vulnerability in the Linux kernel's network subsystem allows use-after-free (UAF) in default_operstate() function during device and network namespace dismantles. This can lead to kernel memory corruption and potential privilege escalation. All Linux systems using affected kernel versions are vulnerable.
💻 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 →⚠️ Risk & Real-World Impact
Worst Case
Kernel panic leading to system crash, or privilege escalation to root via kernel memory corruption.
Likely Case
System instability, kernel crashes, or denial of service due to memory corruption.
If Mitigated
Limited impact if proper kernel hardening and isolation are in place, but still risks system stability.
🎯 Exploit Status
Exploitation requires local access and ability to manipulate network namespaces. Syzbot discovered this through fuzzing.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Fixed in kernel commits: 316183d58319f191e16503bc2dffa156c4442df2, 3265aab0736f78bb218200b06b1abb525c316269, 750e51603395e755537da08f745864c93e3ce741
Vendor Advisory: https://git.kernel.org/stable/c/316183d58319f191e16503bc2dffa156c4442df2
Restart Required: Yes
Instructions:
1. Update Linux kernel to version containing the fix commits. 2. Check with your distribution for specific patched kernel packages. 3. Reboot system after kernel update.
🔧 Temporary Workarounds
Restrict network namespace creation
linuxLimit ability to create network namespaces to reduce attack surface.
sysctl -w kernel.unprivileged_userns_clone=0
sysctl -w user.max_user_namespaces=0
🧯 If You Can't Patch
- Implement strict access controls to prevent unprivileged users from creating network namespaces.
- Monitor system logs for kernel panics or suspicious network namespace operations.
🔍 How to Verify
Check if Vulnerable:
Check kernel version and compare with distribution security advisories. Vulnerable if using kernel versions before the fix commits were applied.Check Version:
uname -rVerify Fix Applied:
Verify kernel version includes the fix commits: 316183d58319f191e16503bc2dffa156c4442df2, 3265aab0736f78bb218200b06b1abb525c316269, or 750e51603395e755537da08f745864c93e3ce741📡 Detection & Monitoring
Log Indicators:
- Kernel panic messages
- KASAN reports of use-after-free in default_operstate() or __dev_get_by_index()
- System crashes during network operations
Network Indicators:
- Unusual network namespace creation patterns
SIEM Query:
source="kernel" AND ("KASAN" OR "use-after-free" OR "default_operstate" OR "__dev_get_by_index")