In Twisted before 19.2.1, twisted.web did not validate or sanitize URIs or HTTP methods, allowing an attacker to inject invalid characters such as CRLF.

Affected: Ubuntu:16.04:LTS: twisted, Ubuntu:18.04:LTS: twisted

it was discovered that Twisted incorrectly validated or sanitized certain URIs or HTTP methods. A remote attacker could use this issue to inject invalid characters and possibly perform header injection attacks. (CVE-2019-12387)

It was discovered that Twisted incorrectly verified XMPP TLS certificates. A remote attacker could possibly use this issue to perform a machine-in-the-middle attack and obtain sensitive information. (CVE-2019-12855)

It was discovered that Twisted incorrectly handled HTTP/2 connections. A remote attacker could possibly use this issue to cause Twisted to hang or consume resources, leading to a denial of service. This issue only affected Ubuntu 18.04 LTS and Ubuntu 19.10. (CVE-2019-9512, CVE-2019-9514, CVE-2019-9515)

Jake Miller and ZeddYu Lu discovered that Twisted incorrectly handled certain content-length headers. A remote attacker could possibly use this issue to perform HTTP request splitting attacks. (CVE-2020-10108, CVE-2020-10109)