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No exploitation reportedFix available

CVE-2021-32066

No exploitation reported by the sources we read.

  • Published2021-08-01
  • WeaknessCWE-755

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

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."

Timeline

dates in UTC
  1. 2021-08-0119:15CVE publishedNVD

Versions per branch

NVD · OSV
Ruby
BranchAffectedFixed in
2.6≥ 2.6.0, ≤ 2.6.7no fix published
2.7≥ 2.7.0, ≤ 2.7.3no fix published
3.0≥ 3.0.0, ≤ 3.0.1no fix published
ruby
BranchAffectedFixed in
3.0≥ 3.0.0, < 3.0.23.0.2
2.7≥ 2.7.0, < 2.7.42.7.4
2.6≥ 2.6.0, < 2.6.82.6.8
ruby-min
BranchAffectedFixed in
3.0≥ 3.0.0, < 3.0.23.0.2
2.7≥ 2.7.0, < 2.7.42.7.4
2.6≥ 2.6.0, < 2.6.82.6.8

1 more product in the sources.

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • jrubyDebian:14all versions · fixed in 9.3.9.0+ds-1
  • jrubyDebian:13all versions · fixed in 9.3.9.0+ds-1
  • jrubyDebian:12all versions · fixed in 9.3.9.0+ds-1
  • jrubyDebian:10all versions · fixed in 9.1.17.0-3+deb10u1
  • rh-ruby26-rubyRed Hat:rhel_software_collections:3::el7all versions · fixed in 0:2.6.9-120.el7and 4 other packages
  • rh-ruby26-rubygem-bigdecimalRed Hat:rhel_software_collections:3::el7all versions · fixed in 0:1.4.1-120.el7
  • rh-ruby26-rubygem-bundlerRed Hat:rhel_software_collections:3::el7all versions · fixed in 0:1.17.2-120.el7
  • rh-ruby26-rubygem-did_you_meanRed Hat:rhel_software_collections:3::el7all versions · fixed in 0:1.3.0-120.el7

418 more package ranges on OSV.dev

Vendor advisories

  • CVE-2021-32066 Red Hat Product Security1,081 products fixed · 16 known affected

    ruby: StartTLS stripping vulnerability in Net::IMAP

    ruby as a component of Red Hat Enterprise Linux 7 · ruby-devel as a component of Red Hat Enterprise Linux 7 · ruby-doc as a component of Red Hat Enterprise Linux 7 · +13 more

  • RHSA-2022:0708 Red Hat Product Security64 products fixed

    Red Hat Security Advisory: rh-ruby26-ruby security, bug fix, and enhancement update

  • RHSA-2022:0672 Red Hat Product Security144 products fixed

    Red Hat Security Advisory: ruby:2.5 security update

  • RHSA-2022:0582 Red Hat Product Security142 products fixed

    Red Hat Security Advisory: ruby:2.6 security update

  • RHSA-2022:0581 Red Hat Product Security92 products fixed

    Red Hat Security Advisory: ruby:2.6 security update

  • RHSA-2022:0544 Red Hat Product Security142 products fixed

    Red Hat Security Advisory: ruby:2.6 security update

4 more advisories

Full record on NVD

Fix

  1. Vendor fix Red Hat Product Security RHSA-2022:0708 · 64 productsFor details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258
  2. No fix planned, says the vendor Red Hat Product Security CVE-2021-32066 · 16 productsOut of support scope

Advisories and patches

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof of concept
Metasploit modules
none listed
Metasploit Framework

Sources

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Published
2021-08-01
Last Modified
2026-06-17
NVD status
Modified
GitHub Advisory
GHSA-gx49-h5r3-q3xj

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 2026-11-08, 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), with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N.

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