CVE-2021-32066

Exp

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."

Published: 2021-08-01 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-32066 is rated Exploit Available (54.6/100): CVSS High severity, with low exploitation likelihood (EPSS 0.10%). 1 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2021-32066

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2021-32066

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2025-12-28 0.16% 0.10% -0.06%
2 2025-12-27 0.10% 0.16% +0.06%
3 2025-11-21 — 0.10% —

Full EPSS history (23 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-32066

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.4 3.1 HIGH
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.
 2.2 5.2 [email protected]
5.8 2.0 MEDIUM
AV:N/AC:M/Au:N/C:P/I:P/A:N Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:N)
No availability impact.
 8.6 4.9 [email protected]

Weakness enumeration for CVE-2021-32066

OS Trackers for CVE-2021-32066

vendor priority summary link
alpine — CVE-2021-32066: 1 source package rows (ruby); 29 state rows across 9 repos (3.11-main, 3.12-main, 3.17-main, 3.18-main, 3.19-main, 3.20-main, 3.21-main, 3.22-main, edge-main); fixed 9, open 20. https://security.alpinelinux.org/vuln/CVE-2021-32066
debian not yet assigned CVE-2021-32066 not yet assigned priority: Debian including 2 source packages (jruby, ruby2.7), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2021-32066
gentoo normal CVE-2021-32066: 1 GLSA(s) (202401-27), 1 atom(s) (dev-lang/ruby); latest impact normal. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2021-32066
redhat medium — https://access.redhat.com/security/cve/CVE-2021-32066
suse high CVE-2021-32066 severity important: SUSE including 361 source package names (2.17-17.3:libruby2_5-2_5-2.5.9-4.20.1, 2.17-17.3:ruby2.5-2.5.9-4.20.1, …), 1144 product×package rows across 262 product lines (Container bci/ruby, Container suse/rmt-server, … (262 product lines)): Fixed 981, Known Affected 160, Known Not Affected 3. https://www.suse.com/security/cve/CVE-2021-32066/
ubuntu medium CVE-2021-32066 medium priority: Ubuntu including 5 source packages (ruby1.9.1, ruby2.0, ruby2.3, ruby2.5, ruby2.7), 44 status rows across 9 suites (bionic, focal, groovy, hirsute, impish, jammy, trusty, upstream, xenial): DNE 33, released 6, needs-triage 5. https://ubuntu.com/security/CVE-2021-32066

Affected software / configurations for CVE-2021-32066

Vendor Product Version Raw CPE
ruby-lang ruby >= 2.6.0, <= 2.6.7 cpe:2.3:a:ruby-lang:ruby:*:*:*:*:*:*:*:*
ruby-lang ruby >= 2.7.0, <= 2.7.3 cpe:2.3:a:ruby-lang:ruby:*:*:*:*:*:*:*:*
ruby-lang ruby >= 3.0.0, <= 3.0.1 cpe:2.3:a:ruby-lang:ruby:*:*:*:*:*:*:*:*
oracle jd_edwards_enterpriseone_tools < 9.2.6.1 cpe:2.3:a:oracle:jd_edwards_enterpriseone_tools:*:*:*:*:*:*:*:*

References for CVE-2021-32066

cvelogic Threat Intelligence