CVE-2016-0772

medium
Published 2016-09-02 · Modified 2026-05-06
CVSS v3
6.5
CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N
CVSS v2
5.8
VIR risk
6.5

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."

Predictions

Exploit likelihood
75%
Patch ETA

Heuristic predictions, AS-IS, for prioritization only.

Mitigations

vendor Authored 2026-05-27

Vendor advisory: debian — https://security-tracker.debian.org/tracker/CVE-2016-0772

vendor Authored 2026-05-27

Vendor advisory: secalert@redhat.com — https://hg.python.org/cpython/rev/d590114c2394

vendor Authored 2026-05-27

Vendor advisory: secalert@redhat.com — https://hg.python.org/cpython/rev/b3ce713fb9be

vendor Authored 2026-05-27

Vendor advisory: secalert@redhat.com — https://hg.python.org/cpython/raw-file/v2.7.12/Misc/NEWS

vendor Authored 2026-05-27

Vendor advisory: secalert@redhat.com — https://docs.python.org/3.5/whatsnew/changelog.html#python-3-5-2

vendor Authored 2026-05-27

Vendor advisory: secalert@redhat.com — https://docs.python.org/3.4/whatsnew/changelog.html#python-3-4-5

vendor Authored 2026-05-27

Vendor advisory: suse — https://www.suse.com/security/cve/CVE-2016-0772.html

OS impact

OSVersionStatusFixed in
suse slesaffected
debian debianbullseyefixed2.7.12~rc1-1

Application impact

VendorProductVersionsFixed
pythonpython3.5.0
pythonpython3.5.1
pythonpython3.0
pythonpython3.0.1
pythonpython3.1.0
pythonpython3.1.1
pythonpython3.1.2
pythonpython3.1.3
pythonpython3.1.4
pythonpython3.1.5
pythonpython3.2.0
pythonpython3.2.1
pythonpython3.2.2
pythonpython3.2.3
pythonpython3.2.4
pythonpython3.2.5
pythonpython3.2.6
pythonpython3.3.0
pythonpython3.3.1
pythonpython3.3.2
pythonpython3.3.3
pythonpython3.3.4
pythonpython3.3.5
pythonpython3.3.6
pythonpython3.4.0
pythonpython3.4.1
pythonpython3.4.2
pythonpython3.4.3
pythonpython3.4.4
pythonpython{"endIncluding":"2.7.11"}

References

CWEs

CWE-693

Verify integrity in audit chain (admin only). AS-IS.