Vulnerabilities
Misconfiguration
Compliance
Cryptography
CVE Vulnerabilities

CVE-2016-0772

Protection Mechanism Failure

Published: Sep 02, 2016 | Modified: May 06, 2026
CVSS 3.x
6.5
MEDIUM
Source:
NVD
CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N
CVSS 2.x
5.8 MEDIUM
AV:N/AC:M/Au:N/C:P/I:P/A:N
RedHat/V2
5.8 MODERATE
AV:N/AC:M/Au:N/C:P/I:P/A:N
RedHat/V3
4.8 MODERATE
CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
Ubuntu
MEDIUM
Vulnerability-free packages from our partners
Additional information
NVDhttps://nvd.nist.gov/vuln/detail/CVE-2016-0772
CWEhttps://cwe.mitre.org/data/definitions/693.html

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.

Weakness

The product does not use or incorrectly uses a protection mechanism that provides sufficient defense against directed attacks against the product.

Affected Software

NameVendorStart VersionEnd Version
PythonPython3.5.0 (including)3.5.0 (including)
PythonPython3.5.1 (including)3.5.1 (including)
Red Hat Enterprise Linux 6RedHatpython-0:2.6.6-66.el6_8*
Red Hat Enterprise Linux 7RedHatpython-0:2.7.5-38.el7_2*
Red Hat Software Collections for Red Hat Enterprise Linux 6RedHatpython27-python-0:2.7.8-18.el6*
Red Hat Software Collections for Red Hat Enterprise Linux 6RedHatpython33-python-0:3.3.2-18.el6*
Red Hat Software Collections for Red Hat Enterprise Linux 6RedHatrh-python34-python-0:3.4.2-14.el6*
Red Hat Software Collections for Red Hat Enterprise Linux 6.6 EUSRedHatpython27-python-0:2.7.8-18.el6*
Red Hat Software Collections for Red Hat Enterprise Linux 6.6 EUSRedHatpython33-python-0:3.3.2-18.el6*
Red Hat Software Collections for Red Hat Enterprise Linux 6.6 EUSRedHatrh-python34-python-0:3.4.2-14.el6*
Red Hat Software Collections for Red Hat Enterprise Linux 6.7 EUSRedHatpython27-python-0:2.7.8-18.el6*
Red Hat Software Collections for Red Hat Enterprise Linux 6.7 EUSRedHatpython33-python-0:3.3.2-18.el6*
Red Hat Software Collections for Red Hat Enterprise Linux 6.7 EUSRedHatrh-python34-python-0:3.4.2-14.el6*
Red Hat Software Collections for Red Hat Enterprise Linux 7RedHatrh-python35-python-0:3.5.1-9.el7*
Red Hat Software Collections for Red Hat Enterprise Linux 7RedHatpython27-python-0:2.7.8-16.el7*
Red Hat Software Collections for Red Hat Enterprise Linux 7RedHatpython33-python-0:3.3.2-16.el7*
Red Hat Software Collections for Red Hat Enterprise Linux 7RedHatrh-python34-python-0:3.4.2-13.el7*
Red Hat Software Collections for Red Hat Enterprise Linux 7.1 EUSRedHatrh-python35-python-0:3.5.1-9.el7*
Red Hat Software Collections for Red Hat Enterprise Linux 7.1 EUSRedHatpython27-python-0:2.7.8-16.el7*
Red Hat Software Collections for Red Hat Enterprise Linux 7.1 EUSRedHatpython33-python-0:3.3.2-16.el7*
Red Hat Software Collections for Red Hat Enterprise Linux 7.1 EUSRedHatrh-python34-python-0:3.4.2-13.el7*
Red Hat Software Collections for Red Hat Enterprise Linux 7.2 EUSRedHatrh-python35-python-0:3.5.1-9.el7*
Red Hat Software Collections for Red Hat Enterprise Linux 7.2 EUSRedHatpython27-python-0:2.7.8-16.el7*
Red Hat Software Collections for Red Hat Enterprise Linux 7.2 EUSRedHatpython33-python-0:3.3.2-16.el7*
Red Hat Software Collections for Red Hat Enterprise Linux 7.2 EUSRedHatrh-python34-python-0:3.4.2-13.el7*
Python2.7Ubuntuesm-infra-legacy/trusty*
Python2.7Ubuntuesm-infra-legacy/xenial*
Python2.7Ubuntuesm-infra/xenial*
Python2.7Ubuntuprecise*
Python2.7Ubuntutrusty*
Python2.7Ubuntutrusty/esm*
Python2.7Ubuntuupstream*
Python2.7Ubuntuvivid/ubuntu-core*
Python2.7Ubuntuwily*
Python2.7Ubuntuxenial*
Python3.2Ubuntuprecise*
Python3.4Ubuntuesm-infra-legacy/trusty*
Python3.4Ubuntutrusty*
Python3.4Ubuntutrusty/esm*
Python3.4Ubuntuvivid/stable-phone-overlay*
Python3.4Ubuntuvivid/ubuntu-core*
Python3.4Ubuntuwily*
Python3.5Ubuntuesm-infra-legacy/trusty*
Python3.5Ubuntuesm-infra-legacy/xenial*
Python3.5Ubuntuesm-infra/xenial*
Python3.5Ubuntutrusty*
Python3.5Ubuntutrusty/esm*
Python3.5Ubuntuupstream*
Python3.5Ubuntuwily*
Python3.5Ubuntuxenial*

References

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