Amazon Linux AMI Security Advisory: ALAS-2019-1298
Advisory Release Date: 2019-10-02 22:59 Pacific
Some HTTP/2 implementations are vulnerable to window size manipulation and stream prioritization manipulation, potentially leading to a denial of service. The attacker requests a large amount of data from a specified resource over multiple streams. They manipulate window size and stream priority to force the server to queue the data in 1-byte chunks. Depending on how efficiently this data is queued, this can consume excess CPU, memory, or both. (CVE-2019-9511 )
Some HTTP/2 implementations are vulnerable to resource loops, potentially leading to a denial of service. The attacker creates multiple request streams and continually shuffles the priority of the streams in a way that causes substantial churn to the priority tree. This can consume excess CPU. (CVE-2019-9513 )
Run yum update nghttp2 to update your system.