Linux Kernel Exploitation: CVE-2025-21756 - #CVE-2025-21756
A critical vulnerability, CVE-2025-21756, has been discovered in the Linux kernel's vsock subsystem, affecting versions prior to 6.6.79, 6.12.16, 6.13.4, and 6.14-rc1. This Use-After-Free (UAF) flaw, dubbed "Attack of the Vsock," stems from improper reference counting during transport reassignment of vsock sockets, enabling local privilege escalation and kernel code execution. Exploitation involves manipulating freed vsock objects, bypassing Kernel Address Space Layout Randomization (kASLR), and hijacking control flow through a Return-Oriented Programming (ROP) chain. A proof-of-concept exploit demonstrates the full attack process, including bypassing AppArmor protections and achieving root access. With a CVSS v3.1 score of 7.8, this vulnerability poses significant risks to virtualized environments, potentially leading to privilege escalation, denial-of-service, and data breaches. Organizations are urged to apply immediate patches and implement mitigation measures such as restricting vsock usage and enhancing security module configurations.