The U.S. Cybersecurity and Infrastructure Security Agency (CISA) this week moved to add a Linux vulnerability dubbed PwnKit to its Known Exploited Vulnerabilities Catalog, citing evidence of active exploitation.

The issue, tracked as CVE-2021-4034 (CVSS score: 7.8), came to light in January 2022 and concerns a case of local privilege escalation in polkit's pkexec utility, which allows an authorized user to execute commands as another user.

Polkit (formerly called PolicyKit) is a toolkit for controlling system-wide privileges in Unix-like operating systems, and provides a mechanism for non-privileged processes to communicate with privileged processes.

Successful exploitation of the flaw could induce pkexec to execute arbitrary code, granting an unprivileged attacker administrative rights on the target machine and compromising the host.

It's not immediately clear how the vulnerability is being weaponized in the wild, nor is there any information on the identity of the threat actor that may be exploiting it.

Also included in the catalog is CVE-2021-30533, a security shortcoming in Chromium-based web browsers that was leveraged by a malvertising threat actor dubbed Yosec to deliver dangerous payloads last year.

Furthermore, the agency added the newly disclosed Mitel VoIP zero-day (CVE-2022-29499) as well as five Apple iOS vulnerabilities (CVE-2018-4344, CVE-2019-8605, CVE-2020-9907, CVE-2020-3837, and CVE-2021-30983) that were recently uncovered as having been abused by Italian spyware vendor RCS Lab.

To mitigate any potential risk of exposure to cyberattacks, it's recommended that organizations prioritize timely remediation of the issues. Federal Civilian Executive Branch Agencies, however, are required to mandatorily patch the flaw by July 18, 2022.