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Amazon Linux 2 : runc (ALASDOCKER-2026-141)

medium Nessus Plugin ID 345805

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Synopsis

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

Description

The version of runc installed on the remote host is prior to 1.3.6-1. It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2DOCKER-2026-141 advisory.

 (*x509.Certificate).VerifyHostname previously called matchHostnames in a loop over all DNS Subject Alternative Name (SAN) entries. This caused strings.Split(host, .) to execute repeatedly on the same input hostname. With a large DNS SAN list, verification costs scaled quadratically based on the number of SAN entries multiplied by the hostname's label count. Because x509.Verify validates hostnames before building the certificate chain, this overhead occurred even for untrusted certificates. (CVE-2026-27145)

 On Unix systems, opening a file in an os.Root improperly follows symlinks to locations outside of the Root when the final path component of the a path is a symbolic link and the path ends in /. For example, 'root.Open(symlink/)' will open symlink even when symlink is a symbolic link pointing outside of the root. (CVE-2026-39822)

 When setting up the container rootfs, setupPtmx and setupDevSymlinks call os.Remove and os.Symlink with a filepath.Join string which allow an image with /dev as a symlink to trick runc into deleting files called ptmx on the host or creating a hardcoded set of symlinks with specific names and targets in an arbitrary pre-existing host directory. (from https://github.com/opencontainers/runc/security/advisories/GHSA- xjvp-4fhw-gc47) (CVE-2026-41579)

 Decoding a maliciously-crafted MIME header containing many invalid encoded-words can consume excessive CPU. (CVE-2026-42504)

 Handshakes which used Encrypted Client Hello could be de-anonymized by a passive network observer due to a disclosure of pre-shared key identities in the unencrypted client hello. (CVE-2026-42505)

 When returning errors, functions in the net/textproto package would include its input as part of the error. This might allow an attacker to inject misleading content to errors that are printed or logged.
 (CVE-2026-42507)

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 'yum update runc' or or 'yum update --advisory ALAS2DOCKER-2026-141' to update your system.

See Also

https://alas.aws.amazon.com//AL2/ALAS2DOCKER-2026-141.html

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

https://explore.alas.aws.amazon.com/CVE-2026-27145.html

https://explore.alas.aws.amazon.com/CVE-2026-39822.html

https://explore.alas.aws.amazon.com/CVE-2026-41579.html

https://explore.alas.aws.amazon.com/CVE-2026-42504.html

https://explore.alas.aws.amazon.com/CVE-2026-42505.html

https://explore.alas.aws.amazon.com/CVE-2026-42507.html

Plugin Details

Severity: Medium

ID: 345805

File Name: al2_ALASDOCKER-2026-141.nasl

Version: 1.1

Type: Local

Agent: unix

Published: 9/14/2026

Updated: 9/14/2026

Supported Sensors: Agentless Assessment, Continuous Assessment, Frictionless Assessment Agent, Frictionless Assessment AWS, Nessus Agent, Tenable Cloud Security, Tenable Self-Hosted Container Security, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 5

Percentile: 93.89

CVSS v2

Risk Factor: Medium

Base Score: 6.8

Temporal Score: 5

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

CVSS Score Source: CVE-2026-39822

CVSS v3

Risk Factor: High

Base Score: 7.8

Temporal Score: 6.8

Vector: CVSS:3.0/AV:L/AC:L/PR:L/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: Medium

Base Score: 4.8

Threat Score: 1.1

Threat Vector: CVSS:4.0/E:U

Vector: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N

CVSS Score Source: CVE-2026-41579

Vulnerability Information

CPE: cpe:/o:amazon:linux:2, p-cpe:/a:amazon:linux:runc-debuginfo, p-cpe:/a:amazon:linux:runc

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

Exploit Ease: No known exploits are available

Patch Publication Date: 9/14/2026

Vulnerability Publication Date: 6/2/2026

Reference Information

CVE: CVE-2026-27145, CVE-2026-39822, CVE-2026-41579, CVE-2026-42504, CVE-2026-42505, CVE-2026-42507

IAVB: 2026-B-0146, 2026-B-0193-S