Amazon Linux 2023 : ruby3.4, ruby3.4-bundled-gems, ruby3.4-default-gems (ALAS2023-2026-1807)

high Nessus Plugin ID 319837

Synopsis

The remote Amazon Linux 2023 host is missing a security update.

Description

It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2023-2026-1807 advisory.

zlib is a Ruby interface for the zlib compression/decompression library. Versions 3.0.0 and below, 3.1.0, 3.1.1, 3.2.0 and 3.2.1 contain a buffer overflow vulnerability in the Zlib::GzipReader. The zstream_buffer_ungets function prepends caller-provided bytes ahead of previously produced output but fails to guarantee the backing Ruby string has enough capacity before the memmove shifts the existing data. This can lead to memory corruption when the buffer length exceeds capacity. This issue has been fixed in versions 3.0.1, 3.1.2 and 3.2.3. (CVE-2026-27820)

Net::IMAP implements Internet Message Access Protocol (IMAP) client functionality in Ruby. Prior to versions 0.4.24, 0.5.14, and 0.6.4, Net::IMAP::ResponseReader has quadratic time complexity when reading large responses containing many string literals. A hostile server can send responses which are crafted to exhaust the client's CPU for a denial of service attack. This issue has been patched in versions 0.4.24, 0.5.14, and 0.6.4. (CVE-2026-42245)

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. (CVE-2026-42246)

Net::IMAP implements Internet Message Access Protocol (IMAP) client functionality in Ruby. From versions 0.4.0 to before 0.4.24, 0.5.0 to before 0.5.14, and 0.6.0 to before 0.6.4, when authenticating a connection with SCRAM-SHA1 or SCRAM-SHA256, a hostile server can perform a computational denial-of-service attack on the client process by sending a big iteration count value. This issue has been patched in versions 0.4.24, 0.5.14, and 0.6.4. (CVE-2026-42256)

Net::IMAP implements Internet Message Access Protocol (IMAP) client functionality in Ruby. Prior to versions 0.4.24, 0.5.14, and 0.6.4, several Net::IMAP commands accept a raw string argument that is sent to the server without validation or escaping. If this string is derived from user-controlled input, it may contain contain CRLF sequences, which an attacker can use to inject arbitrary IMAP commands. This issue has been patched in versions 0.4.24, 0.5.14, and 0.6.4. (CVE-2026-42257)

Net::IMAP implements Internet Message Access Protocol (IMAP) client functionality in Ruby. Prior to versions 0.4.24, 0.5.14, and 0.6.4, symbol arguments to commands are vulnerable to a CRLF Injection / IMAP Command injection via Symbol arguments passed to IMAP commands. This issue has been patched in versions 0.4.24, 0.5.14, and 0.6.4. (CVE-2026-42258)

Tenable has extracted the preceding description block directly from the tested product security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

Solution

Run 'dnf update ruby3.4 --releasever 2023.12.20260608' or or 'dnf update --advisory ALAS2023-2026-1807 --releasever 2023.12.20260608' to update your system.

Plugin Details

Severity: High

ID: 319837

File Name: al2023_ALAS2023-2026-1807.nasl

Version: 1.1

Type: Local

Agent: unix

Family: Amazon Linux Local Security Checks

Published: 6/8/2026

Updated: 6/8/2026

Supported Sensors: Continuous Assessment, Nessus Agent, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 6.7

CVSS v2

Risk Factor: Critical

Base Score: 10

Temporal Score: 7.4

Vector: CVSS2#AV:N/AC:L/Au:N/C:C/I:C/A:C

CVSS Score Source: CVE-2026-42258

CVSS v3

Risk Factor: Critical

Base Score: 9.8

Temporal Score: 8.5

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

CVSS v4

Risk Factor: High

Base Score: 7.6

Threat Score: 4.9

Threat Vector: CVSS:4.0/E:U

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

CVSS Score Source: CVE-2026-42246

Vulnerability Information

CPE: p-cpe:/a:amazon:linux:ruby3.4-rubygem-rdoc, p-cpe:/a:amazon:linux:ruby3.4-rubygem-rake, p-cpe:/a:amazon:linux:ruby3.4-rubygem-racc, p-cpe:/a:amazon:linux:ruby3.4-rubygem-bundler, p-cpe:/a:amazon:linux:ruby3.4-rubygem-io-console, p-cpe:/a:amazon:linux:ruby3.4-rubygem-bigdecimal, p-cpe:/a:amazon:linux:ruby3.4-debugsource, p-cpe:/a:amazon:linux:ruby3.4-rubygem-io-console-debuginfo, p-cpe:/a:amazon:linux:ruby3.4-rubygem-bigdecimal-debuginfo, p-cpe:/a:amazon:linux:ruby3.4-rubygem-psych, p-cpe:/a:amazon:linux:ruby3.4-rubygem-psych-debuginfo, p-cpe:/a:amazon:linux:ruby3.4-rubygem-rbs-debuginfo, p-cpe:/a:amazon:linux:ruby3.4-rubygems-devel, p-cpe:/a:amazon:linux:ruby3.4-rubygem-rbs, p-cpe:/a:amazon:linux:ruby3.4-rubygem-racc-debuginfo, p-cpe:/a:amazon:linux:ruby3.4, p-cpe:/a:amazon:linux:ruby3.4-rubygem-json-debuginfo, p-cpe:/a:amazon:linux:ruby3.4-rubygem-rss, p-cpe:/a:amazon:linux:ruby3.4-libs-debuginfo, p-cpe:/a:amazon:linux:ruby3.4-bundled-gems-debuginfo, p-cpe:/a:amazon:linux:ruby3.4-rubygem-minitest, p-cpe:/a:amazon:linux:ruby3.4-bundled-gems, p-cpe:/a:amazon:linux:ruby3.4-rubygems, p-cpe:/a:amazon:linux:ruby3.4-rubygem-power_assert, p-cpe:/a:amazon:linux:ruby3.4-rubygem-test-unit, cpe:/o:amazon:linux:2023, p-cpe:/a:amazon:linux:ruby3.4-default-gems, p-cpe:/a:amazon:linux:ruby3.4-rubygem-typeprof, p-cpe:/a:amazon:linux:ruby3.4-debuginfo, p-cpe:/a:amazon:linux:ruby3.4-doc, p-cpe:/a:amazon:linux:ruby3.4-rubygem-rexml, p-cpe:/a:amazon:linux:ruby3.4-devel, p-cpe:/a:amazon:linux:ruby3.4-libs, p-cpe:/a:amazon:linux:ruby3.4-rubygem-json, p-cpe:/a:amazon:linux:ruby3.4-rubygem-irb

Required KB Items: Host/local_checks_enabled, Host/AmazonLinux/release, Host/AmazonLinux/rpm-list

Exploit Ease: No known exploits are available

Patch Publication Date: 6/8/2026

Vulnerability Publication Date: 4/16/2026

Reference Information

CVE: CVE-2026-27820, CVE-2026-42245, CVE-2026-42246, CVE-2026-42256, CVE-2026-42257, CVE-2026-42258

Detections

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