cve-2026-31431-mitigation

CVE-2026-31431 Mitigation Script

This repository provides a temporary mitigation and revert script for CVE-2026-31431, a Linux kernel local privilege escalation vulnerability.

Disclaimer

This is a temporary workaround, not a permanent fix. Use at your own risk. Always test in a non-production environment before applying to production systems. Apply official vendor patches as soon as they become available.

About the Vulnerability

CVE-2026-31431 is a local privilege escalation vulnerability in the Linux kernel. It allows a non-privileged user to gain root access by exploiting the kernel crypto interface (AF_ALG). Public proof-of-concept (PoC) exploits are available and have been successfully tested on vulnerable systems.

Mitigation Approach

The exploit relies on the AF_ALG kernel crypto interface. This unloads the vulnerable kernel modules and prevents them from loading again (blacklisting). It also blocks the exploit path.

Repository Contents

• mitigate-cve-2026-31431.sh --> Applies mitigation.
• rev_mitigate-cve-2026-31431.sh --> Reverts mitigation after patching.

Usage

chmod +x mitigate-cve-2026-31431.sh
sudo ./mitigate-cve-2026-31431.sh
sudo reboot

Verify Mitigation

lsmod | egrep 'af_alg|algif' Expected result: no output

Revert Mitigation

Only revert after confirming that a patched kernel has been applied and the system is no longer vulnerable.

chmod +x rev_mitigate-cve-2026-31431.sh
sudo ./rev_mitigate-cve-2026-31431.sh
sudo reboot

Impact of Mitigation

This mitigation disables the following kernel modules:

• af_alg
• algif_aead

Potential impact (rare):

• Applications using AF_ALG for cryptographic operations
• Certain specialized VPN or crypto acceleration configurations
• For most environments, there is no noticeable impact.

Best Practice

• Apply mitigation immediately if vulnerable
• Monitor vendor security updates
• Upgrade to a patched kernel when available
• Test system functionality
• Revert mitigation only if required

Tested On

• Ubuntu 22.04 LTS
• Ubuntu 25.10

Demo

License

MIT License

Final Note

This repository provides a temporary defensive control to reduce risk. Permanent remediation should always be done through official kernel updates.