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GHSA-c2jg-hw38-jrqq
No affected components available
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:
- The Content-Length header value could have a
+or-prefix. - Illegal characters were permitted in chunked extensions, such as the LF (
\n) character. - Chunk lengths, which are expressed in hexadecimal format, could have a prefix of
0x. - HTTP headers were stripped of all leading and trailing ASCII whitespace, rather than only space and HTAB (
\t).
This non-conformant parsing can lead to desync if requests pass through multiple HTTP parsers, potentially resulting in HTTP request smuggling.
Impact
You may be affected if:
- You use Twisted Web's HTTP 1.1 server and/or proxy
- You also pass requests through a different HTTP server and/or proxy
The specifics of the other HTTP parser matter. The original report notes that some versions of Apache Traffic Server and HAProxy have been vulnerable in the past. HTTP request smuggling may be a serious concern if you use a proxy to perform request validation or access control.
The Twisted Web client is not affected. The HTTP 2.0 server uses a different parser, so it is not affected.
Patches
The issue has been addressed in Twisted 22.4.0rc1 and later.
Workarounds
Other than upgrading Twisted, you could:
- Ensure any vulnerabilities in upstream proxies have been addressed, such as by upgrading them
- Filter malformed requests by other means, such as configuration of an upstream proxy
Credits
This issue was initially reported by Zhang Zeyu.
The vulnerability can be exploited over the network without needing physical access. It is difficult for an attacker to exploit this vulnerability and may require special conditions. An attacker does not need any special privileges or access rights. No user interaction is needed for the attacker to exploit this vulnerability. The impact is confined to the system where the vulnerability exists. There is a high impact on the confidentiality of the information. There is a high impact on the integrity of the data. There is a high impact on the availability of the system.
Exploitation activity has been observed. Apply available patches or mitigations urgently.
The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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