Linux Kernel Vulnerability Analysis: CVE-2021-26708

Overview

This repository contains a complete reproduction and analysis of CVE-2021-26708 — a use-after-free vulnerability caused by a race condition in AF_VSOCK socket operations in the Linux kernel (v5.10.12). The entire experimental environment was generated and executed using KernJC, an automated vulnerable environment generation tool for Linux kernel vulnerabilities.

Vulnerability Details

Field	Value
CVE	CVE-2021-26708
Type	Use-After-Free (UAF)
Root Cause	Race condition in `virtio_transport_notify_buffer_size()` via concurrent AF_VSOCK socket operations
Kernel Version	5.10.12
Detection	KASAN (Kernel Address Sanitizer) — full stack trace with allocation/free tracking
Severity	High (CVSS 7.0) — local privilege escalation to root

Repository Contents

Environment

All experiments were conducted within the KernJC automated environment:

References

Ruan et al., "KernJC: Automated Vulnerable Environment Generation for Linux Kernel Vulnerabilities", RAID 2024
CVE-2021-26708 — NVD
vsock_poc by jordan9001

License

This project is licensed under the MIT License — see LICENSE for details.

`KernJC: Automated Vulnerable Environment Generation for Linux Kernel Vulnerabilities.pdf`	KernJC paper (Ruan et al., RAID 2024)
`experiment_report.pdf`	Full experiment report for this CVE reproduction (7 pages)
`poc.c`	Proof-of-concept exploit triggering the race condition (source: jordan9001/vsock_poc)
`kasan_report.txt`	KASAN use-after-free report captured during reproduction
`kernel_config.txt`	Linux kernel `.config` used for the vulnerable build (5.10.12, x86_64)

Host OS	Ubuntu 22.04
QEMU	6.2.0 with KVM + vhost-vsock
Kernel	Linux 5.10.12 (x86_64)
Compiler	GCC 9.5.0
Automation	KernJC v0.8.3

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