A Vulnerability in Confluence Server and Data Center Could Allow for Arbitrary Code Execution

A vulnerability has been discovered in Confluence Server and Data
Center, which could allow for arbitrary code execution. Confluence is a
wiki tool used to help teams collaborate and share knowledge
efficiently. Successful exploitation of this vulnerability could allow
an unauthenticated user to execute arbitrary code on a Confluence Server
or Data Center instance. Depending on the privileges associated with the
instance, an attacker could view, change, or delete data.

US Cyber Command has reported mass exploitation of CVE-2021-26084 and
anticipates accelerated attack volume.

* Confluence Server and Data Center all versions prior to 6.13.23
* Confluence Server and Data Center versions from 6.14.0 prior to 7.4.11
* Confluence Server and Data Center versions from 7.5.0 prior to 7.11.6
* Confluence Server and Data Center versions 7.12.x prior to 7.12.5

We recommend the following actions be taken:

* Apply appropriate patches provided by Atlassian to vulnerable systems
immediately after appropriate testing.
* Run all software as a nonprivileged user (one without administrative
privileges) to diminish the effects of a successful attack.
* Evaluate read, write, and execute permissions on all newly installed
* Apply the Principle of Least Privilege to all systems and services.