The EbmlElement::ReadCodedSizeValue function in libEBML before 1.3.3 allows context-dependent attackers to obtain sensitive information from process heap memory via a crafted length value in an EBML id, which triggers an invalid memory access.
https://github.com/Matroska-Org/libebml/commit/24e5cd7c666b1ddd85619d60486db0a5481c1b90
https://github.com/Matroska-Org/libebml/blob/release-1.3.3/ChangeLog
http://www.debian.org/security/2016/dsa-3538
http://lists.opensuse.org/opensuse-updates/2016-01/msg00035.html
http://lists.matroska.org/pipermail/matroska-users/2015-October/006985.html