CVE-2026-42246

Description

Net::IMAP implements Internet Message Access Protocol (IMAP) client functionality in Ruby. Prior to versions 0.3.10, 0.4.24, 0.5.14, and 0.6.4, a man-in-the-middle attacker can cause Net::IMAP#starttls to return "successfully", without starting TLS. This issue has been patched in versions 0.3.10, 0.4.24, 0.5.14, and 0.6.4.

Status

Show unmaintained releases

Package	Ubuntu Release	Status
ruby2.3	26.10 stonking	Not in release
	26.04 LTS resolute	Not in release
	25.10 questing	Not in release
	24.04 LTS noble	Not in release
	22.04 LTS jammy	Not in release
	16.04 LTS xenial	Fixed in 2.3.1-2~ubuntu16.04.16+esm14
ruby2.5	26.10 stonking	Not in release
	26.04 LTS resolute	Not in release
	25.10 questing	Not in release
	24.04 LTS noble	Not in release
	22.04 LTS jammy	Not in release
	18.04 LTS bionic	Fixed in 2.5.1-1ubuntu1.16+esm8
ruby2.7	26.10 stonking	Not in release
	26.04 LTS resolute	Not in release
	25.10 questing	Not in release
	24.04 LTS noble	Not in release
	22.04 LTS jammy	Not in release
	20.04 LTS focal	Fixed in 2.7.0-5ubuntu1.18+esm5
ruby3.0	26.10 stonking	Not in release
	26.04 LTS resolute	Not in release
	25.10 questing	Not in release
	24.04 LTS noble	Not in release
	22.04 LTS jammy	Fixed in 3.0.2-7ubuntu2.13
ruby3.2	26.10 stonking	Not in release
	26.04 LTS resolute	Not in release
	25.10 questing	Not in release
	24.04 LTS noble	Fixed in 3.2.3-1ubuntu0.24.04.8
	22.04 LTS jammy	Not in release
ruby3.3	26.10 stonking	Not affected
	26.04 LTS resolute	Fixed in 3.3.8-2ubuntu3.1
	25.10 questing	Ignored end of standard support
	24.04 LTS noble	Not in release
	22.04 LTS jammy	Not in release
jruby	26.10 stonking	Needs evaluation
	26.04 LTS resolute	Vulnerable
	25.10 questing	Ignored end of standard support
	24.04 LTS noble	Vulnerable
	22.04 LTS jammy	Not in release
	20.04 LTS focal	Vulnerable
	18.04 LTS bionic	Vulnerable
	16.04 LTS xenial	Vulnerable
	14.04 LTS trusty	Vulnerable

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Severity score breakdown

CVSS version:

Base score 7.6 · High

Base metrics

Parameter	Value
Attack vector	Network
Attack complexity	Low
Attack requirements	Present
Privileges required	None
User interaction	Passive
Vulnerable system - Confidentiality impact	High
Vulnerable system - Integrity impact	High
Vulnerable system - Availability impact	None
Subsequent system - Confidentiality impact	None
Subsequent system - Integrity impact	None
Subsequent system - Availability impact	None

Scores

Parameter	Value
Base score	7.6 · High
Base + Threat score	-
Base + Environmental score	-
Base + Threat + Environmental score	-

Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

Base score 7.4 · High

Base metrics

Parameter	Value
Attack vector	Network
Attack complexity	High
Privileges required	None
User interaction	None
Scope	Unchanged
Confidentiality impact	High
Integrity impact	High
Availability impact	None

Scores

Parameter	Value
Base score	7.4 · High
Exploitability score	-
Impact score	-

Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

References

Related Ubuntu Security Notices (USN)

USN-8431-1
Ruby vulnerabilities
15 June 2026

USN-8478-1
Ruby vulnerabilities
29 June 2026