CVE-2016-0772
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…
Does this matter?
EPSS puts the probability of exploitation in the next 30 days at 15.4%, higher than 97% of all known CVEs. Patch or mitigate before the next change window.
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."
- CVSS 3.0
- 6.5 MEDIUMCVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N
- EPSS
- 15.35% probability · 97th percentile
- Public exploits
- 1 in Exploit-DB · first 3 July 2016
- CISA KEV
- Not listed
- Weakness
- CWE-693
- Affected
- python/python
- Source
- secalert@redhat.com
EPSS moved from 16.4% on 21 September 2026 to 15.4% on 26 October 2026. The dashed line is the ten per cent mark our analysts treat as “patch before the next change window”.
Public exploits (1)
Entries in Exploit-DB that cite this CVE. Links go to the Exploit-DB page and to the file in the public repository; nothing is hosted here. A verified tick means the Exploit-DB team confirmed the exploit works against the stated version.
References
- http://lists.opensuse.org/opensuse-security-announce/2020-01/msg00040.html
- http://rhn.redhat.com/errata/RHSA-2016-1626.html
- http://rhn.redhat.com/errata/RHSA-2016-1627.html
- http://rhn.redhat.com/errata/RHSA-2016-1628.html
- http://rhn.redhat.com/errata/RHSA-2016-1629.html
- http://rhn.redhat.com/errata/RHSA-2016-1630.html
- http://www.openwall.com/lists/oss-security/2016/06/14/9Mailing List
- http://www.securityfocus.com/bid/91225
- http://www.splunk.com/view/SP-CAAAPSV
- http://www.splunk.com/view/SP-CAAAPUE
- https://bugzilla.redhat.com/show_bug.cgi?id=1303647Issue Tracking, Third Party Advisory
- https://docs.python.org/3.4/whatsnew/changelog.html#python-3-4-5Release Notes
- https://docs.python.org/3.5/whatsnew/changelog.html#python-3-5-2Release Notes
- https://hg.python.org/cpython/raw-file/v2.7.12/Misc/NEWSRelease Notes
- https://hg.python.org/cpython/rev/b3ce713fb9bePatch
- https://hg.python.org/cpython/rev/d590114c2394Patch
- https://lists.debian.org/debian-lts-announce/2019/02/msg00011.html
- https://security.gentoo.org/glsa/201701-18
- http://lists.opensuse.org/opensuse-security-announce/2020-01/msg00040.html
- http://rhn.redhat.com/errata/RHSA-2016-1626.html
- http://rhn.redhat.com/errata/RHSA-2016-1627.html
- http://rhn.redhat.com/errata/RHSA-2016-1628.html
- http://rhn.redhat.com/errata/RHSA-2016-1629.html
- http://rhn.redhat.com/errata/RHSA-2016-1630.html
- http://www.openwall.com/lists/oss-security/2016/06/14/9Mailing List
- http://www.securityfocus.com/bid/91225
- http://www.splunk.com/view/SP-CAAAPSV
- http://www.splunk.com/view/SP-CAAAPUE
- https://bugzilla.redhat.com/show_bug.cgi?id=1303647Issue Tracking, Third Party Advisory
- https://docs.python.org/3.4/whatsnew/changelog.html#python-3-4-5Release Notes
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.