CVE-2020-11066: 
PHP vulnerability analysis and mitigation

CVE-2020-11066 is a high-severity vulnerability discovered in TYPO3 CMS Core that affects versions 9.0.0 through 9.5.16 and 10.0.0 through 10.4.1. The vulnerability involves insecure deserialization of user-submitted content that could lead to potential system compromise. The issue was disclosed on May 12, 2020, and was subsequently patched in versions 9.5.17 and 10.4.2 (TYPO3 Advisory).

The vulnerability is related to class destructors causing side-effects when being unserialized. The issue is classified under CWE-502 (Deserialization of Untrusted Data). The CVSS v3.1 score for this vulnerability is rated as High with the following vector: AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:H/A:H/E:F/RL:O/RC:C (TYPO3 Advisory).

When exploited, this vulnerability can result in multiple severe consequences: the potential deletion of arbitrary directories in the file system (if writable for web server) and the ability to trigger message submission via email using the identity of the website (mail relay). However, another insecure deserialization vulnerability is required to actually exploit these aspects (TYPO3 Advisory).

The vulnerability requires calling unserialize() on malicious user-submitted content. While the attack complexity is considered high (AC:H), it requires no privileges (PR:N) and no user interaction (UI:N) to exploit (TYPO3 Advisory).

The recommended mitigation is to update to the patched versions: TYPO3 9.5.17 or 10.4.2. These versions contain fixes for the described vulnerability (TYPO3 Advisory).