CVE-2016-10124 in LCX
Summary
by MITRE
An issue was discovered in Linux Containers (LXC) before 2016-02-22. When executing a program via lxc-attach, the nonpriv session can escape to the parent session by using the TIOCSTI ioctl to push characters into the terminal's input buffer, allowing an attacker to escape the container.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 04/20/2025
The vulnerability CVE-2016-10124 represents a critical container escape flaw in Linux Containers (LXC) that existed prior to the February 22, 2016 release. This security issue specifically affects the lxc-attach utility which is commonly used to attach to running containers. The vulnerability stems from improper handling of terminal input operations during container attachment processes, creating a pathway for privilege escalation and container isolation bypass. The flaw allows an attacker with access to a non-privileged container session to manipulate the terminal input buffer of the host session, effectively breaking the containerization boundaries that are fundamental to container security models.
The technical exploitation of this vulnerability relies on the TIOCSTI ioctl system call, which is designed to inject characters into a terminal's input buffer. In the context of LXC containers, when a user executes lxc-attach to connect to a container, the underlying process inherits terminal characteristics from the parent session. The vulnerability occurs because the container's non-privileged session can leverage the TIOCSTI ioctl to push keystrokes into the parent terminal's input queue, enabling command injection and arbitrary code execution within the host environment. This represents a classic case of improper privilege separation where container boundaries are not properly enforced at the terminal input level.
From an operational perspective, this vulnerability poses significant risks to containerized environments as it allows attackers to escape the isolation provided by containerization technologies. The impact extends beyond simple privilege escalation since successful exploitation can lead to complete host compromise, data exfiltration, and further lateral movement within the network infrastructure. Security professionals must understand that this vulnerability affects not just individual containers but potentially the entire host system, making it a critical concern for organizations relying on LXC containerization for application deployment and isolation. The vulnerability also highlights the importance of proper input validation and privilege management in system utilities that interact with terminal devices.
Organizations should implement immediate mitigations including updating to LXC versions released after February 22, 2016, which contain the necessary patches to address the TIOCSTI ioctl handling. Additional protective measures include disabling the lxc-attach utility for non-privileged users, implementing proper user namespace isolation, and conducting comprehensive security audits of container configurations. The vulnerability aligns with CWE-200, which addresses improper output neutralization for logs, and maps to ATT&CK technique T1068, which covers local privilege escalation through exploitation of system vulnerabilities. Security teams should also consider implementing monitoring solutions that detect unusual ioctl system call patterns and terminal manipulation activities to identify potential exploitation attempts. This vulnerability underscores the critical importance of maintaining up-to-date containerization software and implementing robust security controls around container management utilities to prevent unauthorized access to host systems.