Vulnerability in mitmproxy (CVE-2021-39214)
Summary
Vulnerability in mitmproxy (CVE-2021-39214). Successful exploitation can lead to full system takeover. Mitigation: upgrade to 7.0.3 or later.
Original description
The description as published by the source.
Impact
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 mitmproxy would only see one request, the target server would see multiple requests. A smuggled request is still captured as part of another request's body, but 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 you use mitmproxy to protect an HTTP/1 service, no action is required.
Patches
The vulnerability has been fixed in mitmproxy 7.0.3 and above.
Acknowledgements
We thank João Sobral (@chinchila) for responsibly disclosing this vulnerability to the mitmproxy team.
Timeline
- 2021-09-08: Received initial report for mitmproxy <= 6.0.2.
- 2021-09-08: Requested clarification if 7.x is affected.
- 2021-09-10: Received additional details, 7.x situation still unclear.
- 2021-09-13: Internally determined that 7.x is also affected.
- 2021-09-13: Shared initial fix with researcher.
- 2021-09-14: Received confirmation that fix is working, but H2.TE/H2.CL should also be looked at.
- 2021-09-14: Shared revised fix that includes additional H2.TE mitigations.…
Source: OSV.dev (Open Source Vulnerabilities) NVD GitHub Advisory OSV
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2021-39214 has been found in mitmproxy.
Successful exploitation can lead to full system takeover.
What to do: upgrade mitmproxy to 7.0.3 or later.
If unsure, ask your IT team or search "mitmproxy CVE-2021-39214" on the vendor's site.
CVE-2021-39214 (mitmproxy) — CWE-444
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Patched: 7.0.3 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-444) exists in mitmproxy.
Check the vendor advisory for the affected versions of mitmproxy.
Severity: ?. Successful exploitation can lead to full system takeover.
Update to 7.0.3.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'mitmproxy' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'mitmproxy' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
mitmproxyを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade mitmproxy to 7.0.3ステージング環境で 7.0.3 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Ubuntu UBUNTU-CVE-2021-39214 mitmproxy
References
- advisory nvd.nist.gov
- package github.com
- web github.com
- web github.com