chore(deps): update dependency tornado to v6.4.1 [security] #4847
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This PR contains the following updates:
==6.3.3
->==6.4.1
GitHub Vulnerability Alerts
GHSA-753j-mpmx-qq6g
Summary
When Tornado receives a request with two
Transfer-Encoding: chunked
headers, it ignores them both. This enables request smuggling when Tornado is deployed behind a proxy server that emits such requests. Pound does this.PoC
Transfer-Encoding: chunked
headers:This is because Tornado believes that the request has no message body, so it tries to interpret
1\r\nZ\r\n0\r\n\r\n
as its own request, which causes a 400 response. With a little cleverness involvingchunk-ext
s, you can get Tornado to instead respond 405, which has the potential to desynchronize the connection, as opposed to 400 which should always result in a connection closure.Impact
Anyone using Tornado behind a proxy that forwards requests containing multiple
Transfer-Encoding: chunked
headers is vulnerable to request smuggling, which may entail ACL bypass, cache poisoning, or connection desynchronization.GHSA-w235-7p84-xx57
Summary
Tornado’s
curl_httpclient.CurlAsyncHTTPClient
class is vulnerable to CRLF (carriage return/line feed) injection in the request headers.Details
When an HTTP request is sent using
CurlAsyncHTTPClient
, Tornado does not reject carriage return (\r) or line feed (\n) characters in the request headers. As a result, if an application includes an attacker-controlled header value in a request sent usingCurlAsyncHTTPClient
, the attacker can inject arbitrary headers into the request or cause the application to send arbitrary requests to the specified server.This behavior differs from that of the standard
AsyncHTTPClient
class, which does reject CRLF characters.This issue appears to stem from libcurl's (as well as pycurl's) lack of validation for the
HTTPHEADER
option. libcurl’s documentation states:pycurl similarly appears to assume that the headers adhere to the correct format. Therefore, without any validation on Tornado’s part, header names and values are included verbatim in the request sent by
CurlAsyncHTTPClient
, including any control characters that have special meaning in HTTP semantics.PoC
The issue can be reproduced using the following script:
When the specified server receives the request, it contains the injected header (
Header: Injected
) on its own line:The attacker can also construct entirely new requests using a payload with multiple CRLF sequences. For example, specifying a header value of
\r\n\r\nPOST /attacker-controlled-url HTTP/1.1\r\nHost: 727ymeu841qydmnwlol261ktkkqbe24qt.oastify.com
results in the server receiving an additional, attacker-controlled request:Impact
Applications using the Tornado library to send HTTP requests with untrusted header data are affected. This issue may facilitate the exploitation of server-side request forgery (SSRF) vulnerabilities.
Release Notes
tornadoweb/tornado (tornado)
v6.4.1
Compare Source
v6.4
Compare Source
Configuration
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