An issue was discovered htmlcleaner thru = 2.28 allows attackers to cause a denial of service or other unspecified impacts via crafted object that uses cyclic dependencies.

Multiple race conditions in HtmlCleaner before 2.6, as used in Open-Xchange AppSuite 7.2.2 before rev13 and other products, allow remote authenticated users to read the private e-mail of other persons in opportunistic circumstances by leveraging lack of thread safety and performing a rapid series of (1) mail-sending or (2) draft-saving operations.