{"cve":"CVE-2021-39214","nvd":{"published":"2021-09-16T15:15:07.460","modified":"2026-06-17T04:03:19.593","status":"Modified","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_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","score":9.8},"cwes":["CWE-444"],"references":["https://github.com/mitmproxy/mitmproxy/security/advisories/GHSA-22gh-3r9q-xf38","https://github.com/mitmproxy/mitmproxy/security/advisories/GHSA-22gh-3r9q-xf38"],"products":["mitmproxy:mitmproxy"],"source":"nvd","synced_at":"2026-10-19T21:23:41.316049955+00:00"},"epss":{"cve":"CVE-2021-39214","score":0.01055,"percentile":0.64427,"date":"2026-11-01"},"kev":null,"osv":[{"id":"GHSA-22gh-3r9q-xf38","url":"https://osv.dev/vulnerability/GHSA-22gh-3r9q-xf38","summary":"Lacking Protection against HTTP Request Smuggling in mitmproxy","modified":"2026-07-08T06:27:31.868808645Z","packages":[{"ecosystem":"PyPI","name":"mitmproxy","purl":"pkg:pypi/mitmproxy","ranges":["<7.0.3"],"fixed":["7.0.3"]}]},{"id":"PYSEC-2021-328","url":"https://osv.dev/vulnerability/PYSEC-2021-328","summary":"","modified":"2023-11-08T04:06:33.964757Z","packages":[{"ecosystem":"PyPI","name":"mitmproxy","purl":"pkg:pypi/mitmproxy","ranges":["<7.0.3"],"fixed":["7.0.3"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}