Important: mod_http2 security update (Amazon Linux 2)

Package updates are available for Amazon Linux 2 that fix the following vulnerabilities: CVE-2019-9517: Some HTTP/2 implementations are vulnerable to unconstrained interal data buffering, potentially leading to a denial of service. The attacker opens the HTTP/2 window so the peer can send without constraint; however, they leave the TCP window closed so the peer cannot actually write (many of) the bytes on the wire. The attacker then sends a stream of requests for a large response object. Depending on how the servers queue the responses, this can consume excess memory, CPU, or both. 99999: CVE-2019-9517 HTTP/2: request for large response leads to denial of service CVE-2019-9516: Some HTTP/2 implementations are vulnerable to a header leak, potentially leading to a denial of service. The attacker sends a stream of headers with a 0-length header name and 0-length header value, optionally Huffman encoded into 1-byte or greater headers. Some implementations allocate memory for these headers and keep the allocation alive until the session dies. This can consume excess memory. 1741864: CVE-2019-9516 HTTP/2: 0-length headers lead to denial of service CVE-2019-9511: 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. 1741860: CVE-2019-9511 HTTP/2: large amount of data requests leads to denial of service