CVE-2021-4115 Denial of service in polkitd

Medium 5.5 Published 21 Feb 2022 Updated 3 Aug 2024

An unprivileged user can crash polkit by exhausting file descriptors, causing a denial of service for authorization services.

Exploited in the wild: Not known
Login needed: Any signed-in user
Attackable: Local or same network only
Victim action needed: Not needed
Fix: Available

What is CVE-2021-4115?

CVE-2021-4115 is a medium-severity denial of service vulnerability in Canonical Ubuntu Linux, published on 21 Feb 2022. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

There is a flaw in polkit which can allow an unprivileged user to cause polkit to crash, due to process file descriptor exhaustion. The highest threat from this vulnerability is to availability. NOTE: Polkit process outage duration is tied to the failing process being reaped and a new one being spawned

Weakness: CWE-400

Which versions are affected by CVE-2021-4115?

It affects 6 products.

Linux distribution packages (25)

`polkit` AlmaLinux:8	All versions	`0.115-13.el8_5.2`
`polkit-devel` AlmaLinux:8	All versions	`0.115-13.el8_5.2`
`polkit-docs` AlmaLinux:8	All versions	`0.115-13.el8_5.2`
`polkit-libs` AlmaLinux:8	All versions	`0.115-13.el8_5.2`
`polkit` Red Hat:enterprise_linux:8::baseos	All versions	`0:0.115-13.el8_5.2`
`polkit-debuginfo` Red Hat:enterprise_linux:8::baseos	All versions	`0:0.115-13.el8_5.2`
`polkit-debugsource` Red Hat:enterprise_linux:8::baseos	All versions	`0:0.115-13.el8_5.2`
`polkit-devel` Red Hat:enterprise_linux:8::baseos	All versions	`0:0.115-13.el8_5.2`
`polkit-docs` Red Hat:enterprise_linux:8::baseos	All versions	`0:0.115-13.el8_5.2`
`polkit-libs` Red Hat:enterprise_linux:8::baseos	All versions	`0:0.115-13.el8_5.2`
`polkit-libs-debuginfo` Red Hat:enterprise_linux:8::baseos	All versions	`0:0.115-13.el8_5.2`
`polkit` Rocky Linux:8	All versions	`0:0.115-13.el8_5.2`
`polkit` SUSE:Enterprise Storage 7	All versions	`0.116-3.9.1`
`polkit` SUSE:Linux Enterprise Micro 5.0	All versions	`0.116-3.9.1`
`polkit` SUSE:Linux Enterprise Micro 5.1	All versions	`0.116-3.9.1`
`polkit` SUSE:Linux Enterprise Module for Basesystem 15 SP3	All versions	`0.116-3.9.1`
`polkit` SUSE:Linux Enterprise Real Time 15 SP2	All versions	`0.116-3.9.1`
`polkit` SUSE:Linux Enterprise Server 12 SP5	All versions	`0.113-5.27.1`
`polkit` SUSE:Linux Enterprise Server 15 SP2-LTSS	All versions	`0.116-3.9.1`
`polkit` SUSE:Linux Enterprise Server for SAP Applications 12 SP5	All versions	`0.113-5.27.1`
`polkit` SUSE:Linux Enterprise Server for SAP Applications 15 SP2	All versions	`0.116-3.9.1`
`polkit` SUSE:Linux Enterprise Software Development Kit 12 SP5	All versions	`0.113-5.27.1`
`polkit` SUSE:Linux Enterprise Workstation Extension 12 SP5	All versions	`0.113-5.27.1`
`polkit` openSUSE:Leap 15.3	All versions	`0.116-3.9.1`
`polkit` openSUSE:Tumbleweed	All versions	`0.120-3.1`

Products include Canonical Ubuntu Linux, Debian Debian Linux, Fedoraproject Fedora, Oracle Zfs Storage Appliance Kit, Polkit Project Polkit, Redhat Enterprise Linux.

How do I fix CVE-2021-4115?

Apply the vendor's patch.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2021-4115 being exploited?

There is no known exploitation of CVE-2021-4115 in the wild and no public exploit code.

All Canonical Ubuntu Linux vulnerabilities

Sources

Also known as ALSA-2022:1546, CLSA-2022-1644927378, CLSA-2022-1644927474, DEBIAN-CVE-2021-4115, GHSA-vvr6-r92h-x7jw, MGASA-2022-0080 and 10 more.