CVSS:
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N/E:F/RL:O/RC:C
(3.5)
The login screen of the standalone install tool discloses the full path of the transient data directory (e.g. /var/www/html/var/transient/). This applies to composer-based scenarios only - “classic” non-composer installations are not affected.
Update to TYPO3 version 12.4.8 that fixes the problem described above.
Thanks to Markus Klein who reported and fixed the issue.