CVE-2020-11077: HTTP Smuggling via Transfer-Encoding Header in Puma

Vulnerability summary

CVE-2020-11077 is a high (CVSS 7.5) vulnerability in debian debian_linux. EPSS estimates a 2.88% chance of exploitation in the next 30 days, higher than 86.8% of scored vulnerabilities.

Timeline

1. 22-05-2020
   PublishedVulnerability first disclosed.
2. 04-08-2024
   Last modifiedVulnerability information updated.

Description

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.

• CWE-444Inconsistent Interpretation of HTTP RequestsThe product acts as an intermediary HTTP agent (such as a proxy or firewall) in the data flow between two entities such as a client and server, but it does not interpret malformed HTTP requests or responses in ways that are consistent with how the messages will be processed by those entities that are at the ultimate destination.