--- title: "CVE-2026-42246\n | Ubuntu" description: Ubuntu is an open source software operating system that runs from the desktop, to the cloud, to all your internet connected things. url: https://ubuntu.com/security/CVE-2026-42246?format=md keywords: index, follow --- # CVE-2026-42246 Publication date 9 May 2026 Last updated 29 June 2026 --- Ubuntu priority **Medium** [Why this priority?](https://ubuntu.com/security/cves/about#priority ) ## Cvss 3 Severity Score **7.4 · High** [Score breakdown](https://ubuntu.com/security/CVE-2026-42246?format=md#impact-score) Toggle side navigation ## 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 | 26.04 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 2.3.1-2~ubuntu16.04.16+esm14 Ubuntu Pro | | ruby2.5 | 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 2.5.1-1ubuntu1.16+esm8 Ubuntu Pro | | ruby2.7 | 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 2.7.0-5ubuntu1.18+esm5 Ubuntu Pro | | ruby3.0 | 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 3.0.2-7ubuntu2.13 | | ruby3.2 | 26.04 LTS resolute | Not in release | | 25.10 questing | Not in release | | 24.04 LTS noble | Fixed 3.2.3-1ubuntu0.24.04.8 | | 22.04 LTS jammy | Not in release | | ruby3.3 | 26.04 LTS resolute | Fixed 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 | 26.04 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 | --- * [How can I get the fixes?](https://ubuntu.com/security/cves/about#security) * [What do statuses mean?](https://ubuntu.com/security/cves/about#statuses) ### Get expanded security coverage with Ubuntu Pro Reduce your average CVE exposure time from 98 days to 1 day with expanded CVE patching, ten-years security maintenance and optional support for the full stack of open-source applications. Free for personal use. [Get Ubuntu Pro](https://ubuntu.com/pro) [30-day free trial](https://ubuntu.com/pro/free-trial) ## Severity score breakdown CVSS version: CVSS v4.0 [CVSS v4.0](https://ubuntu.com/security/CVE-2026-42246?format=md) [CVSS v3.0](https://ubuntu.com/security/CVE-2026-42246?format=md) **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 ## References * [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-42246) * [NVD](https://nvd.nist.gov/vuln/detail/CVE-2026-42246) * [Launchpad](https://launchpad.net/bugs/cve/CVE-2026-42246) * [Debian](https://security-tracker.debian.org/tracker/CVE-2026-42246) ### Related Ubuntu Security Notices (USN) + [USN-8431-1](https://usn.ubuntu.com/USN-8431-1) + Ruby vulnerabilities + 15 June 2026 + [USN-8478-1](https://usn.ubuntu.com/USN-8478-1) + Ruby vulnerabilities + 29 June 2026 ### Other references * * * * * * * * *