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.

Affected: Ubuntu:14.04:LTS: curl, Ubuntu:16.04:LTS: curl

It was discovered that curl incorrectly handled certain data. An attacker could possibly use this to cause a denial of service or even to get access to sensitive data. This issue only affected Ubuntu 16.04 LTS and Ubuntu 17.10.

It was discovered that curl could accidentally leak authentication data. An attacker could possibly use this to get access to sensitive information. (CVE-2018-1000007)