CVE-2021-39214: mitmproxy HTTP Request/Response Smuggling

Vulnerability summary

CVE-2021-39214 is a critical (CVSS 9.8) HTTP Request/Response Smuggling vulnerability in mitmproxy. EPSS estimates a 1.05% chance of exploitation in the next 30 days, higher than 64% of scored vulnerabilities.

Timeline

1. 16-09-2021
   PublishedVulnerability first disclosed.
2. 04-08-2024
   Last modifiedVulnerability information updated.

Description

mitmproxy is an interactive, SSL/TLS-capable intercepting proxy. In mitmproxy 7.0.2 and below, a malicious client or server is able to perform HTTP request smuggling attacks through mitmproxy. This means that a malicious client/server could smuggle a request/response through mitmproxy as part of another request/response's HTTP message body. While a smuggled request is still captured as part of another request's body, it does not appear in the request list and does not go through the usual mitmproxy event hooks, where users may have implemented custom access control checks or input sanitization. Unless one uses mitmproxy to protect an HTTP/1 service, no action is required. The vulnerability has been fixed in mitmproxy 7.0.3 and above.

• CWE-444Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')The 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.