Summary
Impact
Twisted Web is vulnerable to request smuggling attacks:
- "When presented with two content-length headers, Twisted Web ignored the first header. When the second content-length was set to zero this caused Twisted Web to interpret the request body as a pipelined request. According to RFC 7230 Section 3.3.3#4, if a message is received with multiple content-length headers with differing value, then the server must reject the message with a 400 response." (Jake Miller of Bishop Fox Security)
- " When presented with a content-length and a chunked encoding header, the content-length took precedence and the remainder of the request body was interpreted by Twisted Web as a pipelined request. According to RFC 7230 Section 3.3.3#3, if a message with both content-length and chunked encoding is accepted, transfer-encoding overrides the content-length." (Jake Miller of Bishop Fox Security)
- "Twisted should not allow BWS between the filed-name and colon." (ZeddYu Lu) closed in 9646
- "Two CL header with different values is also not allowed." (ZeddYu Lu)
- "Only accept identity and chunked Transport-Encoding." (ZeddYu Lu)
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
https://github.com/twisted/twisted/commit/20c787a14a09e7cbd5dfd8df08ceff00d1fcc081
https://github.com/twisted/twisted/commit/4a7d22e490bb8ff836892cc99a1f54b85ccb0281
Frequently Asked Questions
- What is GHSA-8R99-H8J2-RW64? GHSA-8R99-H8J2-RW64 is a medium-severity security vulnerability in twisted (pip), affecting versions < 20.3.0. It is fixed in 20.3.0.
- Which versions of twisted are affected by GHSA-8R99-H8J2-RW64? twisted (pip) versions < 20.3.0 is affected.
- Is there a fix for GHSA-8R99-H8J2-RW64? Yes. GHSA-8R99-H8J2-RW64 is fixed in 20.3.0. Upgrade to this version or later.
- Is GHSA-8R99-H8J2-RW64 exploitable, and should I be worried? Whether GHSA-8R99-H8J2-RW64 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 GHSA-8R99-H8J2-RW64 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 GHSA-8R99-H8J2-RW64? Upgrade
twistedto 20.3.0 or later.