CVE-2022-49599
📋 TL;DR
This CVE describes a race condition vulnerability in the Linux kernel's TCP implementation where concurrent reading and modification of the sysctl_tcp_l3mdev_accept parameter can lead to inconsistent behavior. It affects Linux systems using VRF (Virtual Routing and Forwarding) with TCP connections. The vulnerability could allow attackers to cause denial of service or potentially bypass network isolation.
💻 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 →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
An attacker could cause kernel instability, denial of service, or potentially bypass network isolation controls in VRF environments, leading to unauthorized network access.
Likely Case
Most probable impact is inconsistent TCP connection handling, potential connection drops, or minor performance degradation in systems with concurrent access to the affected sysctl parameter.
If Mitigated
With proper kernel patches applied, the race condition is eliminated through proper synchronization using READ_ONCE() operations.
🎯 Exploit Status
Exploitation requires precise timing to trigger the race condition and may require local access or ability to modify kernel parameters.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Patches available in stable kernel releases via the provided git commits
Vendor Advisory: https://git.kernel.org/stable/c/08a75f10679470552a3a443f9aefd1399604d31d
Restart Required: Yes
Instructions:
1. Update to a patched Linux kernel version. 2. Apply the specific kernel patch from the git references. 3. Reboot the system to load the new kernel.
🔧 Temporary Workarounds
Disable VRF if not needed
linuxIf Virtual Routing and Forwarding is not required for your use case, disabling it eliminates the vulnerability.
# Check if VRF is enabled
sysctl net.ipv4.tcp_l3mdev_accept
# To disable (temporary)
sysctl -w net.ipv4.tcp_l3mdev_accept=0
# To make permanent, add to /etc/sysctl.conf:
echo 'net.ipv4.tcp_l3mdev_accept = 0' >> /etc/sysctl.conf && sysctl -p
🧯 If You Can't Patch
- Restrict access to sysctl parameters to prevent unauthorized modifications
- Implement network segmentation to limit potential impact if exploitation occurs
🔍 How to Verify
Check if Vulnerable:
Check kernel version and if VRF is enabled: uname -r && sysctl net.ipv4.tcp_l3mdev_acceptCheck Version:
uname -rVerify Fix Applied:
Verify kernel version is updated to a patched release and check that READ_ONCE() protections are in the kernel source for sysctl_tcp_l3mdev_accept📡 Detection & Monitoring
Log Indicators:
- Kernel panic logs
- TCP connection anomalies in system logs
- Unexpected VRF routing changes
Network Indicators:
- Unusual TCP connection failures in VRF contexts
- Network isolation bypass attempts
SIEM Query:
source="kernel" AND ("panic" OR "oops" OR "TCP" AND "VRF" AND "error")