Published: 13 August 2019

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.



CVSS 3 base score: 7.5


Package Release Status
Launchpad, Ubuntu, Debian
Released (2.4.41-1)
Ubuntu 18.04 LTS (Bionic Beaver)
Released (2.4.29-1ubuntu4.10)
Ubuntu 16.04 ESM (Xenial Xerus) Not vulnerable
(code not built)
Ubuntu 14.04 ESM (Trusty Tahr) Not vulnerable
(http2 support not implemented)