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CVSS v3.1
N/A
EPSS
15.03%
Published
Sep 2, 2016
Modified
May 6, 2026
Public PoC / Exploit (2)
All weaponized →Links to public security research (Exploit-DB, Nuclei, Trickest, GitHub) for defensive use only.
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."
Weaknesses (CWE)
Affected Products (30)
References (20)