CVE-2021-4034
Description
A local privilege escalation vulnerability was found on polkit's pkexec utility. The pkexec application is a setuid tool designed to allow unprivileged users to run commands as privileged users according predefined policies. The current version of pkexec doesn't handle the calling parameters count correctly and ends trying to execute environment variables as commands. An attacker can leverage this by crafting environment variables in such a way it'll induce pkexec to execute arbitrary code. When successfully executed the attack can cause a local privilege escalation given unprivileged users administrative rights on the target machine.
Summary dbcve.org
A local privilege escalation vulnerability in polkit's pkexec utility stems from incorrect handling of argument count. When invoked with zero arguments, the application attempts to execute the program name as a command, allowing attackers to manipulate environment variables (particularly GCONV_PATH) to inject and execute arbitrary code with elevated privileges.
Mitigation
Apply the vendor-supplied security patch for polkit to the latest version, or temporarily mitigate by removing the setuid bit from /usr/bin/pkexec until patching is possible.