Researcher discovers and patches Linux kernel vulnerabilities
Positive Technologies security researcher Alexander Popov has discovered and fixed five similar issues in the virtual socket implementation of the Linux kernel. These vulnerabilities could be exploited for local privilege escalation, as confirmed by Popov in experiments on Fedora 33 Server. The vulnerabilities, known together as CVE-2021-26708, have received a CVSS v3 base score of 7.0 (high severity).
These vulnerabilities result from race conditions that were implicitly added with virtual socket multi-transport support. They appeared in Linux kernel version 5.5 in November 2019. The vulnerable kernel drivers (CONFIG_VSOCKETS and CONFIG_VIRTIO_VSOCKETS) are shipped as kernel modules in all major GNU/Linux distributions. The vulnerable modules are automatically loaded when an AF_VSOCK socket is created. This ability is available to unprivileged users.