A use-after-free issue was discovered in libwebm through 2018-02-02. If a Vp9HeaderParser was initialized once before, its property frame would not be changed because of code in vp9parser::Vp9HeaderParser::SetFrame. Its frame could be freed while the corresponding pointer would not be updated, leading to a dangling pointer. This is related to the function OutputCluster in webminfo.cc.

In libwebm before 2019-03-08, a NULL pointer dereference caused by the functions OutputCluster and OutputTracks in webminfo.cc will trigger an abort, which allows a DoS attack, a similar issue to CVE-2018-19212.