Linux Kernel Security Patches — CVEs 2026

Overview

Security patches, hardening configurations, and pre-built custom kernel for Linux. Focused on critical vulnerabilities discovered in 2025-2026. Compatible with Debian-based distributions (ParrotOS, Kali, Ubuntu).

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🛡️ Custom Hardened Kernel 6.19.13

Pre-built, hardened Linux kernel with 27+ security mitigations enabled, Dirty Frag LPE patched, and 20+ CVE mitigations applied.

Download (Pre-built .deb)

Package	Size	Download
linux-image	292 MB	Releases
linux-headers	11 MB	Releases
linux-image-dbg	1.3 GB	Releases

Install

sudo dpkg -i linux-image-6.19.13-parrot.custom+2.0-cachyos-g372c9ba96bd4-dirty_6.19.13-g372c9ba96bd4-8_amd64.deb \
            linux-headers-6.19.13-parrot.custom+2.0-cachyos-g372c9ba96bd4-dirty_6.19.13-g372c9ba96bd4-8_amd64.deb
sudo update-grub
sudo reboot

Hardening Applied

Category	Options
Memory Safety	INIT_ON_FREE_DEFAULT_ON, ZERO_CALL_USED_REGS, SHUFFLE_PAGE_ALLOCATOR, SLAB_FREELIST_HARDENED, RANDSTRUCT_PERFORMANCE
Module Security	MODULE_SIG_FORCE, MODULE_SIG_ALL, MODULE_SIG_SHA512
Kernel Lockdown	LOCK_DOWN_KERNEL_FORCE_INTEGRITY
CPU Mitigations	SLS, RETBLEED, SRSO, GDS, RFDS, Spectre BHI, MMIO Stale Data
Scheduler	BORE + CachyOS optimizations
Access Control	SECURITY_DMESG_RESTRICT, STRICT_DEVMEM, IO_STRICT_DEVMEM
Attack Surface	NET_SCH_QFQ disabled (CVE-2026-22976), INET_DIAG_DESTROY disabled

CVEs Patched / Mitigated

CVE	CVSS	Type	Mitigation
Dirty Frag (no CVE)	~9.0	LPE via xfrm-ESP + RxRPC page-cache write	Module blacklist + kernel patch (SKBFL_SHARED_FRAG)
CVE-2026-22976	5.5	NULL deref in sch_qfq	Module disabled (NET_SCH_QFQ=n)
CVE-2025-37916	7.8	UAF in pds_core	Module build (depends on hardware)
CVE-2025-38179	7.8	OOB in cifs	CIFS_SMB_DIRECT not set
CVE-2026-23171	7.8	UAF in bonding	Module build
CVE-2026-23198	7.8	UAF in KVM	Module build
CVE-2026-23336	7.8	UAF in cfg80211	Module build
CVE-2026-31494	7.8	OOB in macb	Module build
CVE-2026-31431	7.8	Copy Fail LPE	✅ Patched
CVE-2026-31589	9.8	UAF in folio_unmap	✅ Patched
CVE-2026-31649	9.8	Integer underflow stmmac	✅ Patched
CVE-2026-31533	7.8	UAF in TLS	✅ Patched
CVE-2026-31408	5.5	UAF in Bluetooth SCO	✅ Patched

Full CVE tracking: kernel-6.19-custom/CVE-TRACKING.md

Build from Source

# Get kernel source
wget https://cdn.kernel.org/pub/linux/kernel/v6.x/linux-6.19.tar.xz
tar xf linux-6.19.tar.xz
cd linux-6.19

# Apply our hardened config
cp configs/defconfig .config
make olddefconfig

# Apply NVIDIA compat patch (if using NVIDIA proprietary driver)
patch -p1 < ../nvidia-compat-mutex_destroy.patch

# Build
make -j$(nproc)
sudo make modules_install
sudo make install
sudo update-grub

Hardening Comparison

How our custom kernel compares against major distro kernels:

Hardening Option	Our Kernel 6.19	Solus LTS 6.18	Debian 6.12
CPU Mitigations (24)	✅ All	✅ All	✅ All
Struct Randomization	✅ PERFORMANCE	❌ NONE	❌ NONE
Module Signing (Force)	✅ SHA-512	❌	❌
Kernel Lockdown	✅ INTEGRITY	❌	❌
INIT_ON_FREE	✅ Zero on kfree	❌	❌
ZERO_CALL_USED_REGS	✅	❌	❌
DMESG_RESTRICT	✅	❌	❌
IO_STRICT_DEVMEM	✅	❌	❌
Dirty Frag LPE	✅ Patched	❌ Vulnerable	❌ Vulnerable

Solus comparison based on PR #8790 (linux-lts 6.18.28).

Kernel Config

• configs/defconfig — boot config (minimal, what ships in /boot)
• configs/defconfig-full — full config with all options
• configs/dirtyfrag.conf — module blacklist for Dirty Frag mitigation

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🔧 CVE Patches

Patch Files

File	CVE	Severity	Description
CVE-2026-31431-copy-fail.patch	CVE-2026-31431	HIGH (7.8)	Copy Fail - Local Privilege Escalation via page cache
CVE-2026-31589-folio-unmap-uaf.patch	CVE-2026-31589	CRITICAL (9.8)	Use-after-free in folio_unmap_invalidate
CVE-2026-31649-stmmac-integer-underflow.patch	CVE-2026-31649	CRITICAL (9.8)	Integer underflow in stmmac Ethernet driver
CVE-2026-31533-tls-uaf.patch	CVE-2026-31533	HIGH (7.8)	Use-after-free in TLS subsystem
CVE-2026-31408-bluetooth-sco-uaf.patch	CVE-2026-31408	MEDIUM (5.5)	Use-after-free in Bluetooth SCO
nvidia-compat-mutex_destroy.patch	N/A (compat)	—	Export mutex_destroy as non-GPL for NVIDIA DKMS

Apply Patches

git clone https://github.com/MethodWhite/kernel-security-patches.git
cd kernel-security-patches

# Download kernel source
apt-get source linux-image-$(uname -r)

# Apply patches
chmod +x apply-kernel-fixes.sh
./apply-kernel-fixes.sh /path/to/kernel/source

# Build and install
cd /path/to/kernel/source
make -j$(nproc)
sudo make modules_install
sudo make install
sudo update-grub
sudo reboot

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🛡️ System Hardening

chmod +x apply-fixes-immediate.sh
sudo ./apply-fixes-immediate.sh

Hardening applied:

• Disable ICMP echo (stealth mode)
• SSH hardening (key-based auth, no root login)
• Service lockdown (disable unused remote services)
• Network hardening (disable source routing, redirects)
• Kernel sysctl security (kptr_restrict, dmesg_restrict, bpf disabled)

Security Verification

uname -r                           # Should show 6.19.13+
cat /etc/modprobe.d/dirtyfrag.conf # Dirty Frag blocked
sysctl kernel.unprivileged_bpf_disabled  # = 1
sysctl kernel.kptr_restrict              # = 2
sysctl kernel.dmesg_restrict             # = 1

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Files Structure

├── configs/
│   ├── defconfig              # Kernel boot config (hardened)
│   ├── defconfig-full         # Full kernel config
│   └── dirtyfrag.conf         # Dirty Frag module blacklist
├── kernel-6.19-custom/
│   ├── CVE-TRACKING.md        # Complete CVE audit for custom kernel
│   └── CHANGELOG.md           # Build changelog
├── CVE-2026-31431-copy-fail.patch
├── CVE-2026-31589-folio-unmap-uaf.patch
├── CVE-2026-31649-stmmac-integer-underflow.patch
├── CVE-2026-31533-tls-uaf.patch
├── CVE-2026-31408-bluetooth-sco-uaf.patch
├── nvidia-compat-mutex_destroy.patch  # NVIDIA DKMS compat (EXPORT_SYMBOL)
├── apply-kernel-fixes.sh              # Kernel patch applicator
├── apply-fixes-immediate.sh           # System hardening
├── apply-security-patches.sh          # Security-only patcher
├── apply-system-hardening.sh          # Full system hardening
├── system-security-analyzer.sh        # Security analysis tool
├── INFORME_ANALISIS_SISTEMA.md        # System analysis (ES)
├── INFORME_COMPLETO_VULNERABILIDADES.md # Vulnerability report (ES)
└── README.md

References

• NVD — National Vulnerability Database
• Linux Kernel Mailing List
• Dirty Frag Disclosure
• Kernel Self Protection Project
• CERT-EU Security Advisories

License

MIT License — Free to use, modify, and distribute.

Disclaimer

Patches provided as-is. Always backup before applying kernel updates. Test in a VM/sandbox before deploying to production.

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Last Updated: 2026-05-12 — Kernel: 6.19.13.parrot.custom+2.0-cachyos (hardened) · 6.12.x (patch series)