Summary
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.
Details
Twisted’s redirectTo function generates an HTTP 302 Redirect response. The response contains an HTML body, built for exceptional cases where the browser doesn’t properly handle the redirect, allowing the user to click a link, navigating them to the specified destination.
The function reflects the destination URL in the HTML body without any output encoding.
# https://github.com/twisted/twisted/blob/trunk/src/twisted/web/_template_util.py#L88
def redirectTo(URL: bytes, request: IRequest) -> bytes:
# ---snip---
content = b"""
<html>
<head>
<meta http-equiv=\"refresh\" content=\"0;URL=%(url)s\">
</head>
<body bgcolor=\"#FFFFFF\" text=\"#000000\">
<a href=\"%(url)s\">click here</a>
</body>
</html>
""" % {
b"url": URL
}
return content
If an attacker has full or partial control over redirect location due to an application bug, also known as an “Open Redirect”, they may inject arbitrary HTML into the response’s body, ultimately leading to an XSS attack.
It’s worth noting that the issue is known to maintainers and tracked with GitHub Issue#9839. The issue description, however, does not make any mention of exploitability and simply states: “…Browsers don't seem to actually render that page…”
PoC
The issue can be reproduced by running the following Twisted-based HTTP server locally:
from twisted.web import server, resource
from twisted.internet import reactor
from twisted.web.util import redirectTo
class Simple(resource.Resource):
isLeaf = True
def render_GET(self, request):
url = request.args[b'url'][0] # <-- open redirect
return redirectTo(url, request)
site = server.Site(Simple())
reactor.listenTCP(9009, site)
reactor.run()
Once running, navigate to the following URL: http://127.0.0.1:9009?url=ws://example.com/"><script>alert(document.location)</script>, and verify that the “alert” dialog was displayed.
Note: Due to the different ways browsers validate the redirect Location header, this attack is possible only in Firefox. All other tested browsers will display an error message to the user and will not render the HTML body.
Impact
If successfully exploited, the issue will allow malicious JavaScript to run in the context of the victim's session. This will in turn lead to unauthorized access/modification to victim's account and information associated with it, or allow for unauthorized operations to be performed within the context of the victim's session.
Untrusted input is rendered as active markup in a victim's browser, which can run script in their session. Typical impact: session or credential theft, and actions taken as the user.
CVE-2024-41810 has a CVSS score of 6.1 (Medium). The vector is network-reachable, no privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (24.7.0rc1); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Remediation advice
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
Frequently Asked Questions
- What is CVE-2024-41810? CVE-2024-41810 is a medium-severity cross-site scripting (XSS) vulnerability in twisted (pip), affecting versions <= 24.3.0. It is fixed in 24.7.0rc1. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
- How severe is CVE-2024-41810? CVE-2024-41810 has a CVSS score of 6.1 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of twisted are affected by CVE-2024-41810? twisted (pip) versions <= 24.3.0 is affected.
- Is there a fix for CVE-2024-41810? Yes. CVE-2024-41810 is fixed in 24.7.0rc1. Upgrade to this version or later.
- Is CVE-2024-41810 exploitable, and should I be worried? Whether CVE-2024-41810 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2024-41810 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2024-41810? Upgrade
twistedto 24.7.0rc1 or later.