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 f
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."
- DLA-1663-1
- DLA-522-1
- DLA-871-1
- openSUSE-SU-2020:0086-1
- openSUSE-SU-2024:10193-1
- openSUSE-SU-2024:10450-1
- openSUSE-SU-2024:10536-1
- openSUSE-SU-2024:11284-1
- RHSA-2016:1626
- RHSA-2016:1627
- RHSA-2016:1628
- RHSA-2016:1629
- RHSA-2016:1630
- SUSE-SU-2016:2106-1
- SUSE-SU-2016:2270-1
- SUSE-SU-2016:2653-1
- SUSE-SU-2016:2859-1
- SUSE-SU-2019:0223-1
- SUSE-SU-2020:0114-1
- SUSE-SU-2020:0234-1
- Published
- Sep 2, 2016
- Updated
- Jun 16, 2026
- EPSS
- 14.5% · 97th percentile
- CWE
- CWE-693
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Report tools
Action score
30
Monitor
Low priority for now.
- CVSS
- 26 / 40 · 6.5 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 4 / 30 · 14.5%
Affected systems
| Vendor | Product | CPE |
|---|---|---|
| python | python | cpe:2.3:a:python:python |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- python pythonup to 2.7.11 inclusive
- python python3.0
- python python3.0.1
- python python3.1.0
- python python3.1.1
- python python3.1.2
- python python3.1.3
- python python3.1.4
- python python3.1.5
- python python3.2.0
- python python3.2.1
- python python3.2.2
- python python3.2.3
- python python3.2.4
- python python3.2.5
- python python3.2.6
- python python3.3.0
- python python3.3.1
- python python3.3.2
- python python3.3.3
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Debian:11 | python2.7 | before 2.7.12~rc1-1 | 2.7.12~rc1-1 |
| Debian:7 | python2.7 | before 2.7.3-6+deb7u3 | 2.7.3-6+deb7u3 |
| Debian:7 | python3.2 | before 3.2.3-7+deb7u1 | 3.2.3-7+deb7u1 |
| Debian:8 | python3.4 | before 3.4.2-1+deb8u2 | 3.4.2-1+deb8u2 |
| openSUSE:Leap 15.1 | python3 | before 3.6.10-lp151.6.7.1 | 3.6.10-lp151.6.7.1 |
| openSUSE:Leap 15.1 | python3-base | before 3.6.10-lp151.6.7.1 | 3.6.10-lp151.6.7.1 |
| openSUSE:Tumbleweed | python | before 2.7.12-1.5 | 2.7.12-1.5 |
| openSUSE:Tumbleweed | python-base | before 2.7.12-1.4 | 2.7.12-1.4 |
| openSUSE:Tumbleweed | python-doc | before 2.7.12-1.3 | 2.7.12-1.3 |
| openSUSE:Tumbleweed | python36 | before 3.6.15-1.1 | 3.6.15-1.1 |
| Red Hat:enterprise_linux:6::client | python | before 0:2.6.6-66.el6_8 | 0:2.6.6-66.el6_8 |
| Red Hat:enterprise_linux:6::client | python-debuginfo | before 0:2.6.6-66.el6_8 | 0:2.6.6-66.el6_8 |
| Red Hat:enterprise_linux:6::client | python-devel | before 0:2.6.6-66.el6_8 | 0:2.6.6-66.el6_8 |
| Red Hat:enterprise_linux:6::client | python-libs | before 0:2.6.6-66.el6_8 | 0:2.6.6-66.el6_8 |
| Red Hat:enterprise_linux:6::client | python-test | before 0:2.6.6-66.el6_8 | 0:2.6.6-66.el6_8 |
| Red Hat:enterprise_linux:6::client | python-tools | before 0:2.6.6-66.el6_8 | 0:2.6.6-66.el6_8 |
| Red Hat:enterprise_linux:6::client | tkinter | before 0:2.6.6-66.el6_8 | 0:2.6.6-66.el6_8 |
| Red Hat:enterprise_linux:7::client | python | before 0:2.7.5-38.el7_2 | 0:2.7.5-38.el7_2 |
| Red Hat:enterprise_linux:7::client | python-debug | before 0:2.7.5-38.el7_2 | 0:2.7.5-38.el7_2 |
| Red Hat:enterprise_linux:7::client | python-debuginfo | before 0:2.7.5-38.el7_2 | 0:2.7.5-38.el7_2 |
| Red Hat:enterprise_linux:7::client | python-devel | before 0:2.7.5-38.el7_2 | 0:2.7.5-38.el7_2 |
| Red Hat:enterprise_linux:7::client | python-libs | before 0:2.7.5-38.el7_2 | 0:2.7.5-38.el7_2 |
| Red Hat:enterprise_linux:7::client | python-test | before 0:2.7.5-38.el7_2 | 0:2.7.5-38.el7_2 |
| Red Hat:enterprise_linux:7::client | python-tools | before 0:2.7.5-38.el7_2 | 0:2.7.5-38.el7_2 |
+74
Same product
python: all recordsOther highest-scoring records for the same primary product.
- CVE-2016-5636Integer overflow in the get_data function in zipimport.c in CPython (aka Python) before 2.7.12, 3.x before 3.4.5, and 3.5.x before 3.5.2 all47Plan
- CVE-2007-4559Directory traversal vulnerability in the (1) extract and (2) extractall functions in the tarfile module in Python allows user-assisted remot47Plan
- CVE-2021-3177Python 3.x through 3.9.1 has a buffer overflow in PyCArg_repr in _ctypes/callproc.c, which may lead to remote code execution in certain Pyth46Plan
- CVE-2014-4650The CGIHTTPServer module in Python 2.7.5 and 3.3.4 does not properly handle URLs in which URL encoding is used for path separators, which al46Plan
- CVE-2018-1000802Python Software Foundation Python (CPython) version 2.7 contains a CWE-77: Improper Neutralization of Special Elements used in a Command ('C45Plan
- CVE-2020-27619In Python 3 through 3.9.0, the Lib/test/multibytecodec_support.py CJK codec tests call eval() on content retrieved via HTTP.42Plan
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| debian:python2.7 | 2.7.12~rc1-1 · Debian:11 | Package registry (OSV) |
| debian:python3.2 | 3.2.3-7+deb7u1 · Debian:7 | Package registry (OSV) |
| debian:python3.4 | 3.4.2-1+deb8u2 · Debian:8 | Package registry (OSV) |
| opensuse:python | 2.7.12-1.5 · openSUSE:Tumbleweed | Package registry (OSV) |
| opensuse:python-base | 2.7.12-1.4 · openSUSE:Tumbleweed | Package registry (OSV) |
| opensuse:python-doc | 2.7.12-1.3 · openSUSE:Tumbleweed | Package registry (OSV) |
| opensuse:python3 | 3.6.10-lp151.6.7.1 · openSUSE:Leap 15.1 | Package registry (OSV) |
| opensuse:python3-base | 3.6.10-lp151.6.7.1 · openSUSE:Leap 15.1 | Package registry (OSV) |
| opensuse:python36 | 3.6.15-1.1 · openSUSE:Tumbleweed | Package registry (OSV) |
| red hat:python | 0:2.6.6-66.el6_8 · Red Hat:enterprise_linux:6::client | Package registry (OSV) |
| red hat:python-debug | 0:2.7.5-38.el7_2 · Red Hat:enterprise_linux:7::client | Package registry (OSV) |
| red hat:python-debuginfo | 0:2.6.6-66.el6_8 · Red Hat:enterprise_linux:6::client | Package registry (OSV) |
| red hat:python-devel | 0:2.6.6-66.el6_8 · Red Hat:enterprise_linux:6::client | Package registry (OSV) |
| red hat:python-libs | 0:2.6.6-66.el6_8 · Red Hat:enterprise_linux:6::client | Package registry (OSV) |
| red hat:python-test | 0:2.6.6-66.el6_8 · Red Hat:enterprise_linux:6::client | Package registry (OSV) |
| red hat:python-tools | 0:2.6.6-66.el6_8 · Red Hat:enterprise_linux:6::client | Package registry (OSV) |
| red hat:rh-python35-python | 0:3.5.1-9.el7 · Red Hat:rhel_software_collections:2::el7 | Package registry (OSV) |
| red hat:rh-python35-python-debug | 0:3.5.1-9.el7 · Red Hat:rhel_software_collections:2::el7 | Package registry (OSV) |
| red hat:rh-python35-python-debuginfo | 0:3.5.1-9.el7 · Red Hat:rhel_software_collections:2::el7 | Package registry (OSV) |
| red hat:rh-python35-python-devel | 0:3.5.1-9.el7 · Red Hat:rhel_software_collections:2::el7 | Package registry (OSV) |
| red hat:tkinter | 0:2.6.6-66.el6_8 · Red Hat:enterprise_linux:6::client | Package registry (OSV) |
| suse:python | 2.7.9-24.1 · SUSE:Linux Enterprise Desktop 12 SP1 | Package registry (OSV) |
| suse:python-base | 2.7.9-24.2 · SUSE:Linux Enterprise Desktop 12 SP1 | Package registry (OSV) |
| suse:python-doc | 2.7.9-24.4 · SUSE:Linux Enterprise Server 12 SP1 | Package registry (OSV) |
| suse:python3 | 3.4.5-17.1 · SUSE:Linux Enterprise Desktop 12 SP1 | Package registry (OSV) |
| suse:python3-base | 3.4.5-17.1 · SUSE:Linux Enterprise Desktop 12 SP1 | Package registry (OSV) |
Exploit status
Proof of concept available
A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.
Evidence
- Exploit-DB entry ×1
Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.
| Source | Kind | Date |
|---|---|---|
| Exploit-DB entry | local | 2016-07-03 |
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
- First PoC-61 d
- Published
- TodaySep 30, 2026+3680 d
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- No account or password is required.
- No user action is required.
- Special conditions such as timing or configuration are required.
If successful
- Confidentiality
- low · data can be read
- Integrity
- high · data or configuration can be modified
- Availability
- none
- Attack vector
- Network
- Attack complexity
- High
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- Low
- Integrity impact
- High
- Availability impact
- None
Weakness class (CWE)
CWE-693 · Protection Mechanism FailureCVSS vector
CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N
nvd-primary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
- Accessing Functionality Not Properly Constrained by ACLsCAPEC-1likelihood: High · High
- Cross Site TracingCAPEC-107likelihood: Medium · Very High
- Directory IndexingCAPEC-127likelihood: High · Medium
- Using Malicious FilesCAPEC-17likelihood: High · Very High
- Encryption Brute ForcingCAPEC-20likelihood: Low · Low
- Exploiting Trust in ClientCAPEC-22likelihood: High · High
- Escaping a Sandbox by Calling Code in Another LanguageCAPEC-237likelihood: Low · Very High
- Using Unpublished Interfaces or FunctionalityCAPEC-36likelihood: Medium · High
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpChange log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
- lists.opensuse.org/opensuse-security-announce/2020-01/msg00040.html
- rhn.redhat.com/errata/RHSA-2016-1626.html
- rhn.redhat.com/errata/RHSA-2016-1627.html
- rhn.redhat.com/errata/RHSA-2016-1628.html
- rhn.redhat.com/errata/RHSA-2016-1629.html
- rhn.redhat.com/errata/RHSA-2016-1630.html
- www.openwall.com/lists/oss-security/2016/06/14/9
- www.securityfocus.com/bid/91225
- www.splunk.com/view/SP-CAAAPSV
- www.splunk.com/view/SP-CAAAPUE
- bugzilla.redhat.com/show_bug.cgi?id=1303647
- docs.python.org/3.4/whatsnew/changelog.html#python-3-4-5
- docs.python.org/3.5/whatsnew/changelog.html#python-3-5-2
- hg.python.org/cpython/raw-file/v2.7.12/Misc/NEWS
- hg.python.org/cpython/rev/b3ce713fb9be
- hg.python.org/cpython/rev/d590114c2394
- lists.debian.org/debian-lts-announce/2019/02/msg00011.html
- security.gentoo.org/glsa/201701-18
Vendor advisories and official records. Exploit/PoC links are deliberately left out.