CVE-2022-24801

Twisted Web HTTP 1.1 Parsing Vulnerability

• CVSS 8.1
• CWE-444 Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
• Input Validation and Sanitization
• Remote

Twisted is an event-based framework for internet applications, supporting Python 3.6+. 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. The issue has been addressed in Twisted 22.4.0rc1. Two workarounds are available: Ensure any vulnerabilities in upstream proxies have been addressed, such as by upgrading them; or filter malformed requests by other means, such as configuration of an upstream proxy.

CVE

CVE-2022-24801

CWE

CWE-444 Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')

CVSS base score

8.1

Published

2022-04-04

OWASP

A04 Insecure Design

Orthogonal defect classification

Function

Code defect classification

Incorrect Functionality

Category

Input Validation and Sanitization

Subcategory

Insecure Parsing or Deserialization

Accessibility scope

Remote

Impact

Denial of Service (DoS)

Fixed by upgrading

Yes

Solution

Update to Twisted 22.4.0rc1 or higher.

from twisted.web import server, resource
from twisted.internet import reactor

class VulnerableResource(resource.Resource):
    isLeaf = True

    def render_GET(self, request):
    # VULNERABLE: This code is susceptible to xss
        # This method is intentionally lenient in parsing
        # HTTP requests, which can lead to vulnerabilities.
        return b"Vulnerable Response"

# Create a Twisted HTTP server with the vulnerable resource
site = server.Site(VulnerableResource())
reactor.listenTCP(8080, site)
reactor.run()

from twisted.web import server, resource
from twisted.internet import reactor

class Simple(resource.Resource):
    isLeaf = True

    def render_GET(self, request):
    # SECURE: This version prevents xss
        return b"Hello, World!"

# Create a Twisted HTTP server
site = server.Site(Simple())
reactor.listenTCP(8080, site)
reactor.run()

@misc{vaitp:cve202224801,
  title        = {{Twisted Web HTTP 1.1 Parsing Vulnerability}},
  author       = {Bogaerts, Fr\'ed\'eric and Ivaki, Naghmeh and Fonseca, Jos\'e},
  year         = {2022},
  note         = {VAITP Python Vulnerability Dataset, entry CVE-2022-24801},
  howpublished = {\url{https://netpack.pt/vaitp/vulnerability/CVE-2022-24801/}}
}