CVE-2021-39214

CRITICAL
Published Sep 16, 20214y ago · Modified Jun 17, 20262w ago
9.8 CVSS 3.1
Critical
Find Similar
Published Sep 16, 2021 4y ago
Last Modified Jun 17, 2026 2w ago

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.

CVSS Details

Base Score
9.8
Exploitability
3.9
Impact
5.9
Vector string
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack Vector Network
Attack Complexity Low
Privileges Required None
User Interaction None
Scope Unchanged
Confidentiality High
Integrity High
Availability High

Threat Intelligence

No active exploitation signals — not in CISA KEV and no EPSS score yet.

Exploit & Patch Status
No Known Exploit
No Patch Available

Weaknesses 1

CWE-444

Affected Products 1

VendorProductVersionRange
mitmproxymitmproxy* ≤7.0.2

References 1

  • github.com https://github.com/mitmproxy/mitmproxy/security/advisories/GHSA-22gh-3r9q-xf38
    Third Party Advisory

Remediation

No remediation data recorded yet

Check vendor advisories and the NVD entry for patch availability.