CVE-2022-39256: 
C# vulnerability analysis and mitigation

A critical vulnerability (CVE-2022-39256) was discovered in Orckestra C1 CMS versions prior to 6.13. The vulnerability allows remote attackers to execute arbitrary code on affected installations of the CMS through deserialization of untrusted data. Authentication is required to exploit this vulnerability, though the authenticated user may unknowingly trigger the exploit by visiting a specially crafted site (GitHub Advisory).

The vulnerability stems from improper deserialization of untrusted data, classified as CWE-502. The issue was addressed in version 6.13 by restricting allowed classes when deserializing user-controlled data and limiting JSON deserialization MaxDepth to 128 (GitHub PR).

When successfully exploited, this vulnerability enables remote attackers to execute arbitrary code on affected C1 CMS installations. The impact is considered critical as it could lead to complete system compromise, though it requires an authenticated user to trigger the exploit (GitHub Advisory).

The vulnerability was patched in C1 CMS version 6.13. Organizations running affected versions should upgrade to version 6.13 or newer immediately. To facilitate this, Orckestra provided free, immediate, and direct access to their automated upgrade feature for any C1 installation from version 5.0 and later (GitHub Release).