# CVE-2016-0772: Python 3.5: The smtplib library in CPython (aka Python) before 2.7.12, 3.x before 3.4.5, and 3.5.x before 3.5.2 does…

CVE-2016-0772 is fixed in Python 3.5 on 1 platform by Python 3.5 3.5.2 (version 3.5.2), released June 26, 2016. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2016-0772
- Priority: Routine
- CVSS: 6.5
- EPSS: 0.1535
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Sep 2, 2016
- Vendor advisory: https://nvd.nist.gov/vuln/detail/CVE-2016-0772

## Description

The smtplib library in CPython (aka Python) before 2.7.12, 3.x before 3.4.5, and 3.5.x before 3.5.2 does not return an error when StartTLS fails, which might allow man-in-the-middle attackers to bypass the TLS protections by leveraging a network position between the client and the registry to block the StartTLS command, aka a "StartTLS stripping attack."

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Windows apps | Python 3.5 | 3.5.2 | [Python 3.5 3.5.2](https://patchblox.com/security/data/fix/windows-app/python.python.3.5-3.5.2.md) | Jun 26, 2016 |

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Data as of 2026-11-07T18:46:35Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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