CVE-2022-49603 – This CVE describes a race condition vulnerabili... (How to Fix)

Q: What is the severity of CVE-2022-49603?

CVE-2022-49603 has a CVSS score of 4.7 (MEDIUM). This CVE describes a race condition vulnerability in the Linux kernel's IP forwarding priority update mechanism. Attackers could potentially cause inconsistent network behavior or denial of service by exploiting concurrent access to the sysctl_ip_fwd_update_priority variable. This affects Linux systems with IP forwarding enabled.

📋 TL;DR

This CVE describes a race condition vulnerability in the Linux kernel's IP forwarding priority update mechanism. Attackers could potentially cause inconsistent network behavior or denial of service by exploiting concurrent access to the sysctl_ip_fwd_update_priority variable. This affects Linux systems with IP forwarding enabled.

💻 Affected Systems

Products:

Linux kernel

Versions: Specific affected versions not explicitly stated in CVE, but patches available for multiple stable branches

Operating Systems: Linux distributions using vulnerable kernel versions

Default Config Vulnerable: ✅ No

Notes: Only affects systems where IP forwarding is enabled and sysctl_ip_fwd_update_priority is being accessed/modified concurrently.

📦 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, network disruption, or inconsistent packet forwarding behavior leading to denial of service on affected systems.

🟠

Likely Case

Inconsistent network behavior or minor performance degradation in systems with heavy concurrent access to the affected sysctl parameter.

🟢

If Mitigated

Minimal impact with proper kernel hardening and limited access to sysctl parameters.

🌐 Internet-Facing: LOW - Requires local access or ability to modify kernel parameters, not directly exploitable from network.

🏢 Internal Only: MEDIUM - Local attackers or compromised services could potentially exploit this to disrupt network functionality.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: NO

Unauthenticated Exploit: ✅ No

Complexity: HIGH

Exploitation requires precise timing and access to modify kernel parameters, making it difficult to weaponize effectively.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Multiple stable kernel versions with commits: 11038fa781ab, 351f81f7d718, 7bf9e18d9a5e, bcc03369d327

Vendor Advisory: https://git.kernel.org/stable/c/11038fa781ab916535c53351537b22d6d405667d

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 matches patched release.

🔧 Temporary Workarounds

Disable IP forwarding

linux

If IP forwarding is not required, disable it to remove attack surface

sysctl -w net.ipv4.ip_forward=0
sysctl -w net.ipv6.conf.all.forwarding=0

Restrict sysctl access

linux

Limit access to kernel parameters to prevent unauthorized modification

chmod 600 /proc/sys/net/ipv4/ip_forward
set appropriate kernel.sysctl permissions in /etc/sysctl.d/

🧯 If You Can't Patch

Restrict user access to systems and implement strict privilege separation
Monitor for unusual sysctl modifications and implement kernel integrity monitoring

🔍 How to Verify

Check if Vulnerable:

Check kernel version against distribution security advisories. Examine if system has IP forwarding enabled: sysctl net.ipv4.ip_forward

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version is updated to patched version and check that READ_ONCE() protection exists in kernel source for sysctl_ip_fwd_update_priority

📡 Detection & Monitoring

Log Indicators:

Kernel oops or warnings related to IP forwarding
Unexpected sysctl parameter changes in audit logs

Network Indicators:

Inconsistent packet forwarding behavior
Unexpected network disruptions

SIEM Query:

source="kernel" AND ("ip_forward" OR "sysctl_ip_fwd_update_priority")

📊 Metadata

CVE ID: CVE-2022-49603

CVSS v3 Score: 4.7 (MEDIUM)

CVSS Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H

CWE: CWE-362

EPSS Score: 0.03% exploit probability (7.5th percentile)

Published: February 26, 2025

Last Updated: October 1, 2025

🔗 References

📤 Share & Export

📄 Export Markdown 📋 Export JSON

🔗 Related Vulnerabilities

If you're affected by CVE-2022-49603, you might also want to check these: