Sequoia

This repository contains a working exploit for CVE-2021-33909 (Sequoia), a local privilege escalation vulnerability in the Linux kernel's filesystem layer. The main exploit logic is implemented in 'exploit.c', which can be compiled to use either the userfaultfd or FUSE mechanism to trigger the vulnerability. The 'exploit.hello.c' file implements a custom FUSE filesystem used as part of the exploit chain. The exploit works by manipulating mount namespaces, temporary directories, and virtual files to corrupt kernel memory and escalate privileges to root. The README provides compilation and usage instructions, and references a detailed writeup by Qualys. The exploit is operational and provides a local root shell if successful. No network endpoints are involved; all actions are performed locally on the target system. The code is well-structured, with clear separation between the main exploit logic and the FUSE helper component.

This repository contains a proof-of-concept (PoC) exploit for CVE-2021-33909, a size_t-to-int vulnerability in the Linux kernel's filesystem layer (commonly known as 'Sequoia'). The repository consists of a README.md with build and usage instructions, and a single C source file (exploit.c) implementing the exploit logic. The exploit works by creating a deeply nested directory structure and manipulating Linux user and mount namespaces to trigger the kernel bug. It interacts with several /proc pseudo-files (uid_map, gid_map, setgroups, mountinfo) and uses temporary directories under /tmp and the current working directory. The exploit is local-only and requires the attacker to execute code on the target system. Its primary purpose is to demonstrate the vulnerability and potentially achieve local privilege escalation on affected Linux systems.