XML External Entity in Dashboard Widget
It has been discovered that RSS widgets are susceptible to XML external entity processing.
This vulnerability is reasonable, but is theoretical - it was not possible to actually reproduce the vulnerability with current PHP versions of supported and maintained system distributions.
At least with libxml2 version 2.9, the processing of XML external entities is disabled per default - and cannot be exploited. Besides that, a valid backend user account is needed.
Update to TYPO3 version 10.4.10 that fixes the problem described.
Thanks to Victoria Lee who reported this issue and to TYPO3 security team member Oliver Hader who fixed the issue.