Microsoft disclosed four actively exploited zero-day vulnerabilities being used to attack on-premises versions of Microsoft Exchange Server. The vulnerabilities identified are CVE-2021-26855, CVE-2021-26857, CVE-2021-26858, and CVE-2021-27065, all of which affect Microsoft Exchange Server. Exchange Online is not affected. In the attacks observed, the threat actor used these vulnerabilities to access on-premises Exchange servers which enabled access to email accounts, and allowed installation of additional malware to facilitate long-term access to victim environments. Microsoft Threat Intelligence Center (MSTIC) attributes this campaign with high confidence to HAFNIUM, a group assessed to be state-sponsored and operating out of China, based on observed victimology, tactics and procedures.

Cacti provides an operational monitoring and fault management framework. Prior to version 1.2.27, an arbitrary file write vulnerability, exploitable through the "Package Import" feature, allows authenticated users having the "Import Templates" permission to execute arbitrary PHP code on the web server. The vulnerability is located within the `import_package()` function defined into the `/lib/import.php` script. The function blindly trusts the filename and file content provided within the XML data, and writes such files into the Cacti base path (or even outside, since path traversal sequences are not filtered). This can be exploited to write or overwrite arbitrary files on the web server, leading to execution of arbitrary PHP code or other security impacts. Version 1.2.27 contains a patch for this issue.