Affected versions of Twisted are vulnerable to HTTP Request Smuggling. The HTTP 1.0 and 1.1 server provided by twisted.web could process pipelined HTTP requests out-of-order, possibly resulting in information disclosure.

Twisted 22.10.0rc1 includes a fix for CVE-2022-39348: NameVirtualHost Host header injection.
https://github.com/twisted/twisted/security/advisories/GHSA-vg46-2rrj-3647

Twisted 22.1 includes a fix for CVE-2022-21712: In affected versions, twisted exposes cookies and authorization headers when following cross-origin redirects. This issue is present in the 'twisted.web.RedirectAgent' and 'twisted.web.BrowserLikeRedirectAgent' functions. There are no known workarounds.

Affected versions of Twisted are vulnerable to XSS. The `twisted.web.util.redirectTo` function contains an HTML injection vulnerability. If application code allows an attacker to control the redirect URL this vulnerability may result in Reflected Cross-Site Scripting (XSS) in the redirect response HTML body.

Twisted 23.10.0rc1 includes a fix for CVE-2023-46137: Disordered HTTP pipeline response in twisted.web. 
#NOTE: The data we include in this advisory differs from the publicly available on nist.nvd.gov. As indicated in the project's changelog, the vulnerability was introduced in Twisted 16.3.0.
https://github.com/twisted/twisted/security/advisories/GHSA-xc8x-vp79-p3wm

Twisted 22.4.0rc1 includes a fix for CVE-2022-24801: Prior to version 22.4.0rc1, the Twisted Web HTTP 1.1 server, located in the 'twisted.web.http' module, parsed several HTTP request constructs more leniently than permitted by RFC 7230. This non-conformant parsing can lead to desync if requests pass through multiple HTTP parsers, potentially resulting in HTTP request smuggling. Users who may be affected use Twisted Web's HTTP 1.1 server and/or proxy and also pass requests through a different HTTP server and/or proxy. The Twisted Web client is not affected. The HTTP 2.0 server uses a different parser, so it is not affected. Two workarounds are available: Ensure any vulnerabilities in upstream proxies have been addressed, such as by upgrading them; or filtering malformed requests by other means, such as configurating an upstream proxy.
https://github.com/twisted/twisted/security/advisories/GHSA-c2jg-hw38-jrqq