Calling unserialize() on malicious user-submitted content can result in the following scenarios:
Another insecure deserialization vulnerability is required to actually exploit mentioned aspects.
Update to TYPO3 versions 9.5.17 or 10.4.2 that fix the problem described.
github.com/FriendsOfPHP/security-advisories/blob/master/typo3/cms-core/CVE-2020-11066.yaml
github.com/FriendsOfPHP/security-advisories/blob/master/typo3/cms/CVE-2020-11066.yaml
github.com/TYPO3/TYPO3.CMS/security/advisories/GHSA-2rxh-h6h9-qrqc
nvd.nist.gov/vuln/detail/CVE-2020-11066
typo3.org/security/advisory/typo3-core-sa-2020-004