事件： qualys 安全研究人员披露 CVE-2021-4034 polkit pkexec 本地提权漏洞细节。
漏洞描述： polkit pkexec 中对命令行参数处理有误，参数注入能够使非特权用户在有漏洞的主机上获取完全 root 权限。

我检测了我的几台 linux 设备都有问题，赶紧来修复一下。
修复方式：
yum update polkit 命令更新解决问题。

[root@NCCLOUD-CPYY-YLZ ~]# yum update polkit
Loaded plugins: fastestmirror
Determining fastest mirrors
base                                                                    | 2.2 kB  00:00:00
epel                                                                    | 3.3 kB  00:00:00
extras-source                                                           | 1.5 kB  00:00:00
mysql-connectors                                                        | 1.5 kB  00:00:00
mysql-tools                                                             | 1.5 kB  00:00:00
mysql56-community                                                       | 1.5 kB  00:00:00
mysql57-community                                                       | 1.5 kB  00:00:00
mysql80-community                                                       | 1.5 kB  00:00:00
updates-source                                                          | 1.5 kB  00:00:00
(1/4): epel/7/x86_64/updateinfo                                         | 1.1 MB  00:00:00
(2/4): epel/7/x86_64/primary                                            | 3.9 MB  00:00:00
(3/4): mysql-tools/primary                                              |  23 kB  00:00:00
(4/4): updates-source/7/x86_64/primary                                  | 7.8 MB  00:00:00
epel                                                                               13728/13728
mysql-tools                                                                            137/137
updates-source                                                                       3411/3411
Resolving Dependencies
--> Running transaction check
---> Package polkit.x86_64 0:0.112-18.el7 will be updated
---> Package polkit.x86_64 0:0.112-26.el7_9.1 will be an update
--> Finished Dependency Resolution

Dependencies Resolved

===============================================================================================
 Package          Arch             Version                      Repository                Size
===============================================================================================
Updating:
 polkit           x86_64           0.112-26.el7_9.1             updates-source           170 k

Transaction Summary
===============================================================================================
Upgrade  1 Package

Total download size: 170 k
Is this ok [y/d/N]: y
Downloading packages:
Delta RPMs disabled because /usr/bin/applydeltarpm not installed.
polkit-0.112-26.el7_9.1.x86_64.rpm                                      | 170 kB  00:00:00
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
  Updating   : polkit-0.112-26.el7_9.1.x86_64                                              1/2
  Cleanup    : polkit-0.112-18.el7.x86_64                                                  2/2
  Verifying  : polkit-0.112-26.el7_9.1.x86_64                                              1/2
  Verifying  : polkit-0.112-18.el7.x86_64                                                  2/2

Updated:
  polkit.x86_64 0:0.112-26.el7_9.1

Complete!