{"id":"CVE-2016-0772","url":"https://www.cyber-defence.io/tools/cve/CVE-2016-0772","generatedAt":"2026-10-27T18:46:09.887Z","title":"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…","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.\"","published":"2016-09-02T14:59:00.000Z","lastModified":"2026-06-17T00:38:12.000Z","status":"Modified","sourceIdentifier":"secalert@redhat.com","cvss":{"version":"3.0","score":6.5,"severity":"MEDIUM","vector":"CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N"},"cwe":["CWE-693"],"affected":["python/python"],"epss":{"score":0.15352,"percentile":0.96754,"date":"2026-10-26","history":[{"date":"2026-09-21","score":0.16399,"percentile":0.96887},{"date":"2026-09-22","score":0.14524,"percentile":0.96479}]},"kev":{"listed":false},"exploits":{"count":1,"verified":false,"firstPublished":"2016-07-03","source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[{"edbId":43500,"kind":"exploit","title":"Python smtplib 2.7.11 / 3.4.4 / 3.5.1 - Man In The Middle StartTLS Stripping","url":"https://www.exploit-db.com/exploits/43500","sourceUrl":"https://gitlab.com/exploit-database/exploitdb/-/blob/main/exploits/multiple/local/43500.txt","file":"exploits/multiple/local/43500.txt","published":"2016-07-03","added":"2018-01-11","updated":"2018-01-11","author":"tintinweb","type":"local","platform":"multiple","port":null,"verified":false,"codes":["CVE-2016-0772"],"tags":null,"aliases":null,"applicationUrl":null,"screenshotUrl":null,"referenceUrl":"https://github.com/tintinweb/pub/tree/11f6ebda59ad878377df78351f8ab580660d0024/pocs/cve-2016-0772"}]},"verdict":{"level":"urgent","text":"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."},"changes":[],"references":[{"url":"http://lists.opensuse.org/opensuse-security-announce/2020-01/msg00040.html","source":"secalert@redhat.com"},{"url":"http://rhn.redhat.com/errata/RHSA-2016-1626.html","source":"secalert@redhat.com"},{"url":"http://rhn.redhat.com/errata/RHSA-2016-1627.html","source":"secalert@redhat.com"},{"url":"http://rhn.redhat.com/errata/RHSA-2016-1628.html","source":"secalert@redhat.com"},{"url":"http://rhn.redhat.com/errata/RHSA-2016-1629.html","source":"secalert@redhat.com"},{"url":"http://rhn.redhat.com/errata/RHSA-2016-1630.html","source":"secalert@redhat.com"},{"url":"http://www.openwall.com/lists/oss-security/2016/06/14/9","tags":["Mailing List"],"source":"secalert@redhat.com"},{"url":"http://www.securityfocus.com/bid/91225","source":"secalert@redhat.com"},{"url":"http://www.splunk.com/view/SP-CAAAPSV","source":"secalert@redhat.com"},{"url":"http://www.splunk.com/view/SP-CAAAPUE","source":"secalert@redhat.com"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=1303647","tags":["Issue Tracking","Third Party Advisory"],"source":"secalert@redhat.com"},{"url":"https://docs.python.org/3.4/whatsnew/changelog.html#python-3-4-5","tags":["Release Notes"],"source":"secalert@redhat.com"},{"url":"https://docs.python.org/3.5/whatsnew/changelog.html#python-3-5-2","tags":["Release Notes"],"source":"secalert@redhat.com"},{"url":"https://hg.python.org/cpython/raw-file/v2.7.12/Misc/NEWS","tags":["Release Notes"],"source":"secalert@redhat.com"},{"url":"https://hg.python.org/cpython/rev/b3ce713fb9be","tags":["Patch"],"source":"secalert@redhat.com"},{"url":"https://hg.python.org/cpython/rev/d590114c2394","tags":["Patch"],"source":"secalert@redhat.com"},{"url":"https://lists.debian.org/debian-lts-announce/2019/02/msg00011.html","source":"secalert@redhat.com"},{"url":"https://security.gentoo.org/glsa/201701-18","source":"secalert@redhat.com"},{"url":"http://lists.opensuse.org/opensuse-security-announce/2020-01/msg00040.html","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"http://rhn.redhat.com/errata/RHSA-2016-1626.html","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"http://rhn.redhat.com/errata/RHSA-2016-1627.html","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"http://rhn.redhat.com/errata/RHSA-2016-1628.html","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"http://rhn.redhat.com/errata/RHSA-2016-1629.html","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"http://rhn.redhat.com/errata/RHSA-2016-1630.html","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"http://www.openwall.com/lists/oss-security/2016/06/14/9","tags":["Mailing List"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"http://www.securityfocus.com/bid/91225","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"http://www.splunk.com/view/SP-CAAAPSV","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"http://www.splunk.com/view/SP-CAAAPUE","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=1303647","tags":["Issue Tracking","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://docs.python.org/3.4/whatsnew/changelog.html#python-3-4-5","tags":["Release Notes"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://docs.python.org/3.5/whatsnew/changelog.html#python-3-5-2","tags":["Release Notes"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://hg.python.org/cpython/raw-file/v2.7.12/Misc/NEWS","tags":["Release Notes"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://hg.python.org/cpython/rev/b3ce713fb9be","tags":["Patch"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://hg.python.org/cpython/rev/d590114c2394","tags":["Patch"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.debian.org/debian-lts-announce/2019/02/msg00011.html","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://security.gentoo.org/glsa/201701-18","source":"af854a3a-2127-422b-91ae-364da2661108"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2016-0772","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}