CVE-2016-0772: python Protection Mechanism Failure
Vulnerability summary
CVE-2016-0772 is a medium (CVSS 6.5) Protection Mechanism Failure vulnerability in python. EPSS estimates a 15.35% chance of exploitation in the next 30 days, higher than 96.7% of scored vulnerabilities. 1 public exploit is recorded.
Not severe (CVSS 6.5, network access); no exploitation reported by the 5 checked sources
Source freshness unavailable
How is this decided?Advisory lineage
Upstream 0 · Downstream 21 · Related 13Timeline
- 02-09-2016PublishedVulnerability first disclosed.
- 05-08-2024Last modifiedVulnerability information updated.
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 metrics
4 scores · 3 sources · 2 versions- OSV · UbuntuEcosystem advisory · calculated6.5MediumCVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N
- OSV · DebianEcosystem advisory · calculated6.5MediumCVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N
EPSS trend
Probability
15.35%
Chance of exploitation in the next 30 days
Percentile
97%
Versus all other CVEs
30-day change
Increase +0.83 pp
From 14.52% on 04-10-2026
Known exploited
Compare KEV catalogs
CISA KEVNot in the CISA KEV catalog.
ENISA CNWNot in the ENISA CNW catalog.
CIRCLNot in the CIRCL catalog.
Public exploits
1 foundPython smtplib 2.7.11 / 3.4.4 / 3.5.1 - Man In The Middle StartTLS Stripping
Maturity: poc
Weaknesses
CWE · root causeAffected systems
Known conditions: network-reachable, no authentication, no user interaction (CVSS vector). Other conditions: not stated in public data.
Ubuntu3 products
- python2.7< 2.7.6-8ubuntu0.3 | < 2.7.12-1ubuntu0~16.04.1
- python3.4< 3.4.3-1ubuntu1~14.04.5
- python3.5< 3.5.2-2ubuntu0~16.04.4~14.04.1 | < 3.5.2-2ubuntu0~16.04.1
Debian2 products
- python2.7< 2.7.12~rc1-1
- python3.2< 3.2.3-7+deb7u1
Python1 product
- pythonEOL3.5.0 | 3.5.1 | 3.0 | 3.0.1 | 3.1.0 | 3.1.1 | 3.1.2 | 3.1.3 | 3.1.4 | 3.1.5 | 3.2.0 | 3.2.1 | 3.2.2 | 3.2.3 | 3.2.4 | 3.2.5 | 3.2.6 | 3.3.0 | 3.3.1 | 3.3.2 | 3.3.3 | 3.3.4 | 3.3.5 | 3.3.6 | 3.4.0 | 3.4.1 | 3.4.2 | 3.4.3 | 3.4.4 | ≤ 2.7.11
3 vendors · 6 products
References
22 links- www.splunk.com/view/SP-CAAAPUEX Refsource CONFIRM
- www.splunk.com/view/SP-CAAAPSVX Refsource CONFIRM
