libxls through version 1.6.3 contains a use of uninitialized memory vulnerability in the OLE container parser. Memory allocated for the Master Sector Allocation Table (MSAT) in readMSAT() is not fully initialized before being consumed by ole2validatesectorchain(), which may result in application crashes or potential information disclosure when processing a crafted XLS file

A use-of-uninitialized memory vulnerability exists in libxls 1.6.3 when parsing malformed XLS files. The issue is reachable via xlsparseWorkBook() and is triggered by uninitialized heap memory originating from the OLE layer (ole2read). The flaw is detectable with MemorySanitizer (MSAN) and can lead to undefined behavior, incorrect parsing logic, or potential information disclosure.