SB20261109188 - Ubuntu update for ruby2.3, ruby2.5

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Main Vulnerability Database SB20261109188

SB20261109188 - Ubuntu update for ruby2.3, ruby2.5

Published: November 9, 2026

Security Bulletin ID SB20261109188
CSH Severity
Medium
Patch available
YES
Number of vulnerabilities 2
Exploitation vector Remote access
Highest impact

Breakdown by Severity

Medium 100%
  • Low
  • Medium
  • High
  • Critical

Description

This security bulletin contains information about 2 vulnerabilities.


1) Not Failing Securely ('Failing Open') (CVE-ID: CVE-2026-42246)

CWE-ID: CWE-636 - Not Failing Securely (\'Failing Open\')

CVSSv4: 7 [CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:A/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N]


The vulnerability allows an unauthenticated network attacker to bypass TLS and expose sensitive information transmitted by an IMAP client.

The vulnerability exists due to net-imap accepting an early success response during a STARTTLS upgrade of a plaintext connection without ensuring TLS is established. An unauthenticated network attacker can intercept the connection and inject a predictably tagged response before the command finishes, leaving subsequent traffic unencrypted when the client does not explicitly verify TLS.


2) Command injection (CVE-ID: CVE-2026-42257)

CWE-ID: CWE-77 - Command injection

CVSSv4: 6.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:H/VA:L/SC:N/SI:N/SA:N]


The vulnerability allows an unprivileged local attacker to execute arbitrary IMAP commands through an application's authenticated connection to a mail server.

The vulnerability exists due to missing validation and escaping of raw arguments in net-imap commands when an application passes unvalidated, user-controlled input to affected methods. An unprivileged local attacker can insert CRLF sequences into these arguments to inject additional commands, such as deleting mailboxes, during normal application use.


Remediation

Install update from vendor's website.

References