Published: 24 January 2018
libcurl 7.49.0 to and including 7.57.0 contains an out bounds read in code handling HTTP/2 trailers. It was reported (https://github.com/curl/curl/pull/2231) that reading an HTTP/2 trailer could mess up future trailers since the stored size was one byte less than required. The problem is that the code that creates HTTP/1-like headers from the HTTP/2 trailer data once appended a string like `:` to the target buffer, while this was recently changed to `: ` (a space was added after the colon) but the following math wasn't updated correspondingly. When accessed, the data is read out of bounds and causes either a crash or that the (too large) data gets passed to client write. This could lead to a denial-of-service situation or an information disclosure if someone has a service that echoes back or uses the trailers for something.
From the Ubuntu security team
leosilva> vulnerability code was introduced after version 7.47 leosilva> trusty and precise/esm are not-affected.
CVSS 3 base score: 9.1
Launchpad, Ubuntu, Debian
|Ubuntu 18.04 LTS (Bionic Beaver)||
|Ubuntu 16.04 LTS (Xenial Xerus)||
|Ubuntu 14.04 ESM (Trusty Tahr)||