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Not in CISA KEV
MEDIUM severity

CVE-2026-40606 — mitmproxy

MEDIUM

CVE-2026-40606 is a medium-severity (CVSS 4.8) CWE-90 vulnerability in mitmproxy. A fix is available for mitmproxy — see the affected versions and patch details below.

ProxyAuth Addon LDAP Injection in mitmproxy

Also known asGHSA-527g-3w9m-29hvPYSEC-2026-92
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Nov 6, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

  • CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-40606.

EPSS Exploitation Probability

via FIRST.org ↗
0.2%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs6th percentile — riskier than 6% of all scored CVEsHighest risk
0.00%0.25%0.50%0.76%0.0%0.2%May 26Sep 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected
🐍mitmproxy

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

Description

Impact

In mitmproxy 12.2.1 and below, the builtin LDAP proxy authentication does not correctly sanitize the username when querying the LDAP server. This allows a malicious client to bypass authentication.

Only mitmproxy instances using the proxyauth option with LDAP are affected. This option is not enabled by default.

Patches

The vulnerability has been fixed in mitmproxy 12.2.2 and above.

Acknowledgements

We thank Yue (Knox) Liu (@yueyueL) for responsibly disclosing this vulnerability to the mitmproxy team.

Timeline

  • 2025-12-08: Received initial report.
  • 2025-12-09: Verified report and confirmed receipt.
  • 2026-01-02: Informed researcher that patch will be part of the next regular patch release.
  • 2026-04-12: Published patch release and advisory.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐍PyPImitmproxyall versions12.2.2pip install --upgrade 'mitmproxy==12.2.2'

Affected Products

1 product · 1 configurations
Application
mitmproxymitmproxy
< 12.2.2
range

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for mitmproxy, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update mitmproxy to 12.2.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-40606 is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

### Impact In mitmproxy 12.2.1 and below, the builtin LDAP proxy authentication does not correctly sanitize the username when querying the LDAP server. This allows a malicious client to bypass authentication. Only mitmproxy instances using the `proxyauth` option with LDAP are affected. This option is not enabled by default. ### Patches The vulnerability has been fixed in mitmproxy 12.2.2 and above. ### Acknowledgements We thank Yue (Knox) Liu (@yueyueL) for responsibly disclosing this vulnerability to the mitmproxy team. ### Timeline - **2025-12-08**: Received initial report. - **2025-
O3 Security · Impact-Aware SCA

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CVE-2026-40606: mitmproxy — Fixed in 12.2.2