CVE-2022-49577
📋 TL;DR
This CVE describes a race condition vulnerability in the Linux kernel's UDP implementation where the sysctl_udp_l3mdev_accept parameter can be read while being modified concurrently, potentially causing inconsistent behavior. It affects Linux systems with specific kernel versions that handle UDP packets with L3 master device routing. The vulnerability requires local access to exploit.
💻 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 →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 with local access could potentially cause kernel instability, denial of service, or information disclosure by manipulating the UDP L3 master device acceptance behavior during concurrent access.
Likely Case
Local privilege escalation is unlikely; most probable impact is system instability or denial of service affecting UDP networking functionality.
If Mitigated
With proper kernel hardening and access controls, impact is minimal as it requires local access and specific timing conditions.
🎯 Exploit Status
Race conditions are difficult to exploit reliably; no known public exploits at time of CVE publication
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Kernel versions containing commits: 3d72bb4188c708bb16758c60822fc4dda7a95174, 3f2ac2d6511bb0652abf4d7388d65bb9ff1c641c, cb0d28934ca10f99c47e2c6f451405d6c954fe48, f39b03bd727a8fea62e82f10fe2e0d753b9930ff, fcaef69c79ec222e55643e666b80b221e70fa6a8
Vendor Advisory: https://git.kernel.org/stable/c/3d72bb4188c708bb16758c60822fc4dda7a95174
Restart Required: Yes
Instructions:
1. Update Linux kernel to patched version from your distribution vendor. 2. Reboot system to load new kernel. 3. Verify kernel version after reboot.
🔧 Temporary Workarounds
Restrict sysctl access
linuxLimit access to sysctl parameters to prevent unauthorized modification
chmod 600 /proc/sys/net/ipv4/udp_l3mdev_accept
echo 'kernel.sysrq = 0' >> /etc/sysctl.conf
sysctl -p
Disable UDP L3 master device functionality
linuxSet udp_l3mdev_accept to 0 to disable the vulnerable feature
echo 0 > /proc/sys/net/ipv4/udp_l3mdev_accept
echo 'net.ipv4.udp_l3mdev_accept = 0' >> /etc/sysctl.conf
sysctl -p
🧯 If You Can't Patch
- Implement strict access controls to prevent local users from modifying sysctl parameters
- Monitor system logs for unusual UDP behavior or kernel panics
🔍 How to Verify
Check if Vulnerable:
Check kernel version and compare with patched versions from distribution vendor; examine if system uses UDP L3 master device routingCheck Version:
uname -rVerify Fix Applied:
Verify kernel version includes the fix commits; check that READ_ONCE() protection is present in udp.c source📡 Detection & Monitoring
Log Indicators:
- Kernel panic logs
- UDP socket errors in system logs
- Unusual sysctl modification attempts in audit logs
Network Indicators:
- UDP packet processing anomalies
- Increased UDP error rates
SIEM Query:
source="kernel" AND ("panic" OR "oops") OR source="audit" AND "sysctl" AND "udp_l3mdev"🔗 References
- https://git.kernel.org/stable/c/3d72bb4188c708bb16758c60822fc4dda7a95174
- https://git.kernel.org/stable/c/3f2ac2d6511bb0652abf4d7388d65bb9ff1c641c
- https://git.kernel.org/stable/c/cb0d28934ca10f99c47e2c6f451405d6c954fe48
- https://git.kernel.org/stable/c/f39b03bd727a8fea62e82f10fe2e0d753b9930ff
- https://git.kernel.org/stable/c/fcaef69c79ec222e55643e666b80b221e70fa6a8
