view_help.php in the backend help system in TYPO3 4.5.x before 4.5.19, 4.6.x before 4.6.12 and 4.7.x before 4.7.4 allows remote authenticated backend users to unserialize arbitrary objects and possibly execute arbitrary PHP code via an unspecified parameter, related to a "missing signature (HMAC)."
AV:N/AC:H/Au:S/C:P/I:P/A:P
This vulnerability has a 2.12% probability of being exploited in the next 30 days, ranking higher than 81% of all scored CVEs.