FERRAMENTAS LINUX: Critical Linux Kernel Bugs: The "EntrySign" AMD Microcode Flaw & Over 100 Other CVEs – How to Secure Ubuntu 22.04 & 24.04 Forever

Stop rebooting blindly! Fix Linux kernel bugs (EntrySign, over 100 CVEs) in Ubuntu 22.04/24.04. Check, patch, or block with our script & iptables guide.

Historical context (April 2026): A massive kernel update (USN-8179-3) was released, including the EntrySign flaw (CVE-2024-36347) affecting AMD Zen processors, plus fixes for MIPS, PowerPC, x86, netfilter, KVM, and filesystems like ext4 and btrfs.

But instead of chasing each month’s news, use this guide as your permanent checklist for any future Linux kernel vulnerability.

1. How to check if you are vulnerable (Ubuntu/Debian commands)

Run these commands today and after every kernel update announcement:

# Check your current kernel version
uname -r

# For Ubuntu 22.04/24.04 – see if you're on an affected HWE or generic kernel
dpkg -l | grep linux-image- | grep -E "6.8.0-(110|105[12])"

# Verify if your AMD CPU needs EntrySign microcode fix
grep "model name" /proc/cpuinfo | head -1
sudo dmesg | grep -i "microcode.*error"

If uname -r shows 6.8.0-110-generic (or older) on Ubuntu 22.04, or 6.8.0-1052- on 24.04 – you are vulnerable.

2. Automation script to apply the fix (bash – works on Ubuntu, Debian, RHEL, Fedora)

Save this as and run with sudo:

#!/bin/bash
# Linux kernel vulnerability fixer – works on major distros
set -e

echo "🔍 Detecting distro..."
if [ -f /etc/os-release ]; then
    . /etc/os-release
    OS=$ID
    VER=$VERSION_ID
fi

case $OS in
    ubuntu|debian)
        echo "🟡 Updating kernel packages..."
        apt update && apt upgrade -y linux-image-$(uname -r | cut -d'-' -f1-2) linux-headers-$(uname -r) 
        echo "✅ Reboot required: sudo reboot"
        ;;
    rhel|centos|fedora)
        echo "🟡 Updating kernel (RHEL family)..."
        dnf update kernel -y
        echo "✅ Reboot required: sudo reboot"
        ;;
    *)
        echo "⚠️ Unknown distro. Manually update kernel."
        ;;
esac

echo "✔️ After reboot, verify with: uname -r"

Why this works for years: It doesn’t hardcode version numbers. It grabs the current kernel’s base name.

3. Alternative mitigation if you can’t update now (no reboot, no downtime)

Use AppArmor (Ubuntu default) and to block exploit vectors until you can reboot.

Block unknown microcode loading (mitigates EntrySign):

# Restrict access to microcode update interface
sudo aa-complain /etc/apparmor.d/usr.sbin.irqbalance 2>/dev/null || echo "AppArmor not active"
# For a stronger shot: blacklist the microcode module
echo "blacklist microcode" | sudo tee /etc/modprobe.d/disable-microcode.conf
sudo update-initramfs -u

Network-based mitigation (for CVEs in netfilter, , Bluetooth):

# Block new unusual network connections (example for SMB/CIFS bug)
sudo iptables -A INPUT -p tcp --dport 445 -j DROP
sudo iptables -A INPUT -p udp --dport 137:138 -j DROP
# Disable IPv6 if you don't need it (mitigates many network CVEs)
echo "net.ipv6.conf.all.disable_ipv6 = 1" | sudo tee -a /etc/sysctl.conf
sudo sysctl -p

Important: These are emergency stopgaps – not a permanent fix. Reboot into the patched kernel within 30 days.

Important Book

Linux Kernel Programming – Second Edition by - Amazon.

Why this instead of a random course:

This book teaches you to understand dmesg errors, rebuild kernel modules after ABI changes (exactly what USN-8179-3 warns about), and write security-focused device drivers. After reading chapters 4-7, you’ll never blindly paste commands again – you’ll debug the next 100 CVEs yourself.

Affiliate disclosure: As an Amazon Associate, I earn from qualifying purchases. This helps me keep writing in-depth security guides – at no extra cost to you.).

Conclusion: Stop reacting, start automating

Here's the hard truth: Another kernel update will land next month. And the month after that. And each time, you'll be back here, scanning CVE lists, holding your breath during reboots, and hoping nothing breaks.

The sysadmins who sleep well at night don't have magic powers. They have systems.