CVE-2020-11077: HTTP Smuggling via Transfer-Encoding Header in Puma
Impact This is a similar but different vulnerability to the one patched in 3.12.5 and 4.3.4.
A client could smuggle a request through a proxy, causing the proxy to send a response back to another unknown client.
If the proxy uses persistent connections and the client adds another request in via HTTP pipelining, the proxy may mistake it as the first request's body. Puma, however, would see it as two requests, and when processing the second request, send back a response that the proxy does not expect. If the proxy has reused the persistent connection to Puma to send another request for a different client, the second response from the first client will be sent to the second client.
Patches
The problem has been fixed in Puma 3.12.6 and Puma 4.3.5.
For more information
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Other sources
In Puma (RubyGem) before 4.3.5 and 3.12.6, a client could smuggle a request through a proxy, causing the proxy to send a response back to another unknown client. If the proxy uses persistent connections and the client adds another request in via HTTP pipelining, the proxy may mistake it as the first request's body. Puma, however, would see it as two requests, and when processing the second request, send back a response that the proxy does not expect. If the proxy has reused the persistent connection to Puma to send another request for a different client, the second response from the first client will be sent to the second client. This is a similar but different vulnerability from CVE-2020-11076. The problem has been fixed in Puma 3.12.6 and Puma 4.3.5.
— Ubuntu
Affected Software
Event History
Frequently Asked Questions
What is the impact of CVE-2020-11077?
This vulnerability allows a client to smuggle a request through a proxy, causing the proxy to send a response back to another unknown client.
Which versions of Puma are affected by CVE-2020-11077?
Puma versions 4.0.0 to 4.3.5 and versions 3.12.6 and below are affected.
What is the severity of CVE-2020-11077?
The severity of this vulnerability is rated as medium with a CVSS score of 6.8.
How can I fix CVE-2020-11077?
To fix this vulnerability, update Puma to version 4.3.5 or version 3.12.6.
Where can I find more information about CVE-2020-11077?
More information about CVE-2020-11077 can be found at the following references: [GitHub Advisory](https://github.com/puma/puma/security/advisories/GHSA-w64w-qqph-5gxm), [Puma History](https://github.com/puma/puma/blob/master/History.md#434435-and-31253126--2020-05-22), and [NVD](https://nvd.nist.gov/vuln/detail/CVE-2020-11077).