--- title: "CVE-2016-0772\n | Ubuntu" description: Ubuntu is an open source software operating system that runs from the desktop, to the cloud, to all your internet connected things. url: https://ubuntu.com/security/CVE-2016-0772?format=md keywords: index, follow --- # CVE-2016-0772 Publication date 2 September 2016 Last updated 25 August 2025 --- Ubuntu priority **Medium** [Why this priority?](https://ubuntu.com/security/cves/about#priority ) ## Cvss 3 Severity Score **6.5 · Medium** [Score breakdown](https://ubuntu.com/security/CVE-2016-0772?format=md#impact-score) Toggle side navigation ## 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." [Read the notes from the security team](https://ubuntu.com/security/CVE-2016-0772?format=md#notes) ## Status Show unmaintained releases | Package | Ubuntu Release | Status | | --- | --- | --- | | python2.7 | 23.04 lunar | Not in release | | 22.10 kinetic | Not affected | | 22.04 LTS jammy | Not affected | | 21.10 impish | Not affected | | 21.04 hirsute | Not affected | | 20.10 groovy | Not affected | | 20.04 LTS focal | Not affected | | 19.10 eoan | Not affected | | 19.04 disco | Not affected | | 18.04 LTS bionic | Not affected | | 17.04 zesty | Not affected | | 16.10 yakkety | Not affected | | 16.04 LTS xenial | Fixed 2.7.12-1ubuntu0~16.04.1 | | 15.10 wily | Ignored end of life | | 14.04 LTS trusty | Fixed 2.7.6-8ubuntu0.3 | | 12.04 LTS precise | Fixed 2.7.3-0ubuntu3.9 | | python3.2 | 23.04 lunar | Not in release | | 22.10 kinetic | Not in release | | 22.04 LTS jammy | Not in release | | 21.10 impish | Not in release | | 21.04 hirsute | Not in release | | 20.10 groovy | Not in release | | 20.04 LTS focal | Not in release | | 19.10 eoan | Not in release | | 19.04 disco | Not in release | | 18.04 LTS bionic | Not in release | | 17.04 zesty | Not in release | | 16.10 yakkety | Not in release | | 16.04 LTS xenial | Not in release | | 15.10 wily | Not in release | | 14.04 LTS trusty | Not in release | | 12.04 LTS precise | Fixed 3.2.3-0ubuntu3.8 | | python3.4 | 23.04 lunar | Not in release | | 22.10 kinetic | Not in release | | 22.04 LTS jammy | Not in release | | 21.10 impish | Not in release | | 21.04 hirsute | Not in release | | 20.10 groovy | Not in release | | 20.04 LTS focal | Not in release | | 19.10 eoan | Not in release | | 19.04 disco | Not in release | | 18.04 LTS bionic | Not in release | | 17.04 zesty | Not in release | | 16.10 yakkety | Not in release | | 16.04 LTS xenial | Not in release | | 15.10 wily | Ignored end of life | | 14.04 LTS trusty | Fixed 3.4.3-1ubuntu1~14.04.5 | | 12.04 LTS precise | Not in release | | python3.5 | 23.04 lunar | Not in release | | 22.10 kinetic | Not in release | | 22.04 LTS jammy | Not in release | | 21.10 impish | Not in release | | 21.04 hirsute | Not in release | | 20.10 groovy | Not in release | | 20.04 LTS focal | Not in release | | 19.10 eoan | Not in release | | 19.04 disco | Not in release | | 18.04 LTS bionic | Not in release | | 17.04 zesty | Not affected | | 16.10 yakkety | Not affected | | 16.04 LTS xenial | Fixed 3.5.2-2ubuntu0~16.04.1 | | 15.10 wily | Ignored end of life | | 14.04 LTS trusty | Fixed 3.5.2-2ubuntu0~16.04.4~14.04.1 | | 12.04 LTS precise | Not in release | --- * [How can I get the fixes?](https://ubuntu.com/security/cves/about#security) * [What do statuses mean?](https://ubuntu.com/security/cves/about#statuses) * [Patch details](https://ubuntu.com/security/CVE-2016-0772?format=md#patch-details) ## Notes --- ### [sbeattie](https://launchpad.net/~sbeattie) issue is fixed for xenial/python3.5 and xenial/python2.7 for packages in xenial-updates, but not xenial-security ### Patch details For informational purposes only. We recommend not to cherry-pick updates. [How can I get the fixes?](https://ubuntu.com/security/cves/about#security) | Package | Patch details | | --- | --- | | python2.7 | * Upstream: | | python3.4 | * Upstream: | ## Severity score breakdown CVSS version: CVSS v3.0 **Base score** 6.5 · Medium * Base metrics | Parameter | Value | | --- | --- | | Attack vector | Network | | Attack complexity | High | | Privileges required | None | | User interaction | None | | Scope | Unchanged | | Confidentiality impact | Low | | Integrity impact | High | | Availability impact | None | * Scores | Parameter | Value | | --- | --- | | Base score | 6.5 · Medium | | Exploitability score | - | | Impact score | - | **Vector:** CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N ## References * [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-0772) * [NVD](https://nvd.nist.gov/vuln/detail/CVE-2016-0772) * [Launchpad](https://launchpad.net/bugs/cve/CVE-2016-0772) * [Debian](https://security-tracker.debian.org/tracker/CVE-2016-0772) ### Related Ubuntu Security Notices (USN) + [USN-3134-1](https://usn.ubuntu.com/USN-3134-1) + Python vulnerabilities + 22 November 2016 ### Other references * *