ruby net-imap up to 0.3.9/0.4.23/0.5.13/0.6.3 Net::IMAP error condition

Summaryinfo

A vulnerability marked as problematic has been reported in ruby net-imap up to 0.3.9/0.4.23/0.5.13/0.6.3. Affected is the function Net::IMAP. The manipulation leads to error condition. This vulnerability is documented as CVE-2026-42246. The attack can be initiated remotely. There is not any exploit available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability was found in ruby net-imap up to 0.3.9/0.4.23/0.5.13/0.6.3 and classified as problematic. This issue affects the function Net::IMAP. The manipulation with an unknown input leads to a error condition vulnerability. Using CWE to declare the problem leads to CWE-392. The product encounters an error but does not provide a status code or return value to indicate that an error has occurred. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

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.

It is possible to read the advisory at github.com. The identification of this vulnerability is CVE-2026-42246 since 04/25/2026. The exploitation is known to be difficult. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Technical details of the vulnerability are known, but there is no available exploit.

The vulnerability scanner Nessus provides a plugin with the ID 321185 (Ubuntu 16.04 LTS / 18.04 LTS : Ruby vulnerabilities (USN-8431-1)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 0.3.10, 0.4.24, 0.5.14 or 0.6.4 eliminates this vulnerability. The upgrade is hosted for download at github.com. Applying the patch 0ede4c40b1523dfeaf95777b2678e54cc0fd9618 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (321185) and CERT Bund (WID-SEC-2026-2117). Be aware that VulDB is the high quality source for vulnerability data.

Affected

• Red Hat Enterprise Linux
• RESF Rocky Linux
• HCL BigFix
• Oracle Linux

Productinfo

Type

• Programming Language Software

Vendor

• ruby

Name

• net-imap

Version

• 0.3.0
• 0.3.1
• 0.3.2
• 0.3.3
• 0.3.4
• 0.3.5
• 0.3.6
• 0.3.7
• 0.3.8
• 0.3.9
• 0.4.0
• 0.4.1
• 0.4.2
• 0.4.3
• 0.4.4
• 0.4.5
• 0.4.6
• 0.4.7
• 0.4.8
• 0.4.9
• 0.4.10
• 0.4.11
• 0.4.12
• 0.4.13
• 0.4.14
• 0.4.15
• 0.4.16
• 0.4.17
• 0.4.18
• 0.4.19
• 0.4.20
• 0.4.21
• 0.4.22
• 0.4.23
• 0.5.0
• 0.5.1
• 0.5.2
• 0.5.3
• 0.5.4
• 0.5.5
• 0.5.6
• 0.5.7
• 0.5.8
• 0.5.9
• 0.5.10
• 0.5.11
• 0.5.12
• 0.5.13
• 0.6.0
• 0.6.1
• 0.6.2
• 0.6.3

License

• open-source

Website

• Product: https://github.com/ruby/net-imap/

CPE 2.3info

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CPE 2.2info

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Entryinfo

Be aware that VulDB is the high quality source for vulnerability data.

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