CVE-2021-3444

CVE-2021-3444 is a Linux kernel vulnerability in the bpf verifier, affecting various Linux distributions, including Canonical and Debian. It stems from improper handling of mod32 destination register truncation when the source register is zero. This flaw allows a local attacker, with the ability to load bpf programs, to achieve out-of-bounds reads for information disclosure and potentially out-of-bounds writes leading to code execution. The vulnerability is rated High severity (CVSS 7.8), indicating a low attack complexity and requiring local user privileges, but with high impact on confidentiality, integrity, and availability. Currently, there is no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage surrounding this CVE. Patches are available in Linux stable kernels 5.11.2, 5.10.19, and 5.4.101.