CVE-2021-32066
CVSS v3
7.4
HIGH
EPSS Score
2.9 %
exploit probability, as of 2026-09-25
CISA KEV
No
known exploited
Exploitation
—
SSVC status
Description
An issue was discovered in Ruby through 2.6.7, 2.7.x through 2.7.3, and 3.x through 3.0.1. Net::IMAP does not raise an exception when StartTLS fails with an an unknown response, 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."
Technical details
- Published
- 2021-08-01
Frequently asked questions
What is CVE-2021-32066?
An issue was discovered in Ruby through 2.6.7, 2.7.x through 2.7.3, and 3.x through 3.0.1. Net::IMAP does not raise an exception when StartTLS fails with an an unknown response, 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."
Is CVE-2021-32066 actively exploited?
Active exploitation of CVE-2021-32066 has not been confirmed. Its EPSS score was 2.9% on 2026-09-25, the estimated probability of exploitation in the next 30 days.
What is the CVSS score for CVE-2021-32066?
CVE-2021-32066 has a CVSS v3 base score of 7.4 (HIGH severity).
Is CVE-2021-32066 affecting your environment?
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