CVE-2026-31431 - Copy Fail

This vulnerability allows an unprivileged local attacker to gain root privileges on a vulnerable Linux system.

⚠️ DISCLAIMER

This code is provided for educational and security research purposes only.
It demonstrates a hypothetical vulnerability (CVE-2026-31431) in the Linux kernel's AF_ALG socket interface.
Do not run this on any system you do not own or have explicit written permission to test.
Misuse of this code may violate laws and regulations.

📜 Description

CVE-2026-31431 (disclosed 2026) is a copy-on-write / length confusion bug in the authencesn(hmac(sha256),cbc(aes)) AEAD implementation.
By crafting specific sendmsg() control messages with zero-length buffers, an attacker can trigger a kernel splice() operation to overwrite adjacent memory pages – leading to arbitrary file corruption.

This PoC targets /usr/bin/su to modify its binary payload in 4‑byte chunks, then executes it to demonstrate privilege escalation.

🚀 Features

• Abuses AF_ALG, SOL_ALG socket options
• Uses splice() + sendmsg() for zero‑copy data transfer
• Decompresses and writes a hidden payload
• Colored terminal output (green author tag / blue execution)