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Amazon Linux 2 : ruby, --advisory ALAS2-2026-3284 (ALAS-2026-3284)

high Nessus Plugin ID 314590

Synopsis

The remote Amazon Linux 2 host is missing a security update.

Description

The version of ruby installed on the remote host is prior to 2.0.0.648-36. It is, therefore, affected by a vulnerability as referenced in the ALAS2-2026-3284 advisory.

 ERB is a templating system for Ruby. Ruby 2.7.0 (before ERB 2.2.0 was published on rubygems.org) introduced an `@_init` instance variable guard in `ERB#result` and `ERB#run` to prevent code execution when an ERB object is reconstructed via `Marshal.load` (deserialization). However, three other public methods that also evaluate `@src` via `eval()` were not given the same guard: `ERB#def_method`, `ERB#def_module`, and `ERB#def_class`. An attacker who can trigger `Marshal.load` on untrusted data in a Ruby application that has `erb` loaded can use `ERB#def_module` (zero-arg, default parameters) as a code execution sink, bypassing the `@_init` protection entirely. ERB 4.0.3.1, 4.0.4.1, 6.0.1.1, and 6.0.4 patch the issue. (CVE-2026-41316)

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

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

Solution

Run 'yum update ruby' or or 'yum update --advisory ALAS2-2026-3284' to update your system.

See Also

https://alas.aws.amazon.com/faqs.html

https://explore.alas.aws.amazon.com/CVE-2026-41316.html

https://alas.aws.amazon.com//AL2/ALAS2-2026-3284.html

Plugin Details

Severity: High

ID: 314590

File Name: al2_ALAS-2026-3284.nasl

Version: 1.1

Type: Local

Agent: unix

Published: 5/14/2026

Updated: 5/14/2026

Supported Sensors: Agentless Assessment, Continuous Assessment, Frictionless Assessment Agent, Frictionless Assessment AWS, Nessus Agent, Nessus

Risk Information

VPR

Risk Factor: High

Score: 7.4

CVSS v2

Risk Factor: High

Base Score: 7.6

Temporal Score: 5.6

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

CVSS Score Source: CVE-2026-41316

CVSS v3

Risk Factor: High

Base Score: 8.1

Temporal Score: 7.1

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

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

Vulnerability Information

CPE: p-cpe:/a:amazon:linux:ruby-doc, p-cpe:/a:amazon:linux:ruby-tcltk, p-cpe:/a:amazon:linux:ruby-irb, p-cpe:/a:amazon:linux:rubygem-rake, p-cpe:/a:amazon:linux:rubygem-psych, p-cpe:/a:amazon:linux:ruby-devel, p-cpe:/a:amazon:linux:ruby-libs, p-cpe:/a:amazon:linux:ruby, p-cpe:/a:amazon:linux:rubygem-json, p-cpe:/a:amazon:linux:rubygems, p-cpe:/a:amazon:linux:rubygem-bigdecimal, p-cpe:/a:amazon:linux:rubygems-devel, cpe:/o:amazon:linux:2, p-cpe:/a:amazon:linux:rubygem-minitest, p-cpe:/a:amazon:linux:rubygem-io-console, p-cpe:/a:amazon:linux:ruby-debuginfo, p-cpe:/a:amazon:linux:rubygem-rdoc

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

Exploit Ease: No known exploits are available

Patch Publication Date: 5/14/2026

Vulnerability Publication Date: 4/24/2026

Reference Information

CVE: CVE-2026-41316