Azure Linux 3.0 Security Update: CBL-Mariner Releases (CVE-2026-39821)

critical Nessus Plugin ID 317702

Synopsis

The remote Azure Linux host is missing one or more security updates.

Description

The version of CBL-Mariner Releases installed on the remote Azure Linux 3.0 host is prior to tested version. It is, therefore, affected by a vulnerability as referenced in the CVE-2026-39821 advisory.

- The ToASCII and ToUnicode functions incorrectly accept Punycode-encoded labels that decode to an ASCII- only label. For example, ToUnicode(xn--example-.com) incorrectly returns the name example.com rather than an error. This behavior can lead to privilege escalation in programs using the idna package. For example, a program which performs privilege checks on the ASCII hostname May reject example.com but permit xn--example-.com. If that program subsequently converts the ASCII hostname to Unicode, it will inadvertently permits access to the Unicode name example.com. (CVE-2026-39821)

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

Solution

Update the affected packages.

Plugin Details

Severity: Critical

ID: 317702

File Name: azure_linux_CVE-2026-39821.nasl

Version: 1.1

Type: Local

Family: Azure Linux Local Security Checks

Published: 5/29/2026

Updated: 5/29/2026

Supported Sensors: Nessus

Risk Information

VPR

Risk Factor: High

Score: 7.1

CVSS v2

Risk Factor: High

Base Score: 9.4

Temporal Score: 7

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

CVSS Score Source: CVE-2026-39821

CVSS v3

Risk Factor: Critical

Base Score: 9.6

Temporal Score: 8.3

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

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

Vulnerability Information

CPE: p-cpe:/a:microsoft:azure_linux:keda, x-cpe:/o:microsoft:azure_linux, p-cpe:/a:microsoft:azure_linux:gh, p-cpe:/a:microsoft:azure_linux:kata-containers, p-cpe:/a:microsoft:azure_linux:docker-compose, p-cpe:/a:microsoft:azure_linux:opa, p-cpe:/a:microsoft:azure_linux:cloud-provider-kubevirt, p-cpe:/a:microsoft:azure_linux:skopeo, p-cpe:/a:microsoft:azure_linux:ignition-flatcar, p-cpe:/a:microsoft:azure_linux:multus, p-cpe:/a:microsoft:azure_linux:jx, p-cpe:/a:microsoft:azure_linux:docker-buildx, p-cpe:/a:microsoft:azure_linux:coredns, p-cpe:/a:microsoft:azure_linux:cf-cli, p-cpe:/a:microsoft:azure_linux:kata-containers-cc, p-cpe:/a:microsoft:azure_linux:containerd2, p-cpe:/a:microsoft:azure_linux:flannel, p-cpe:/a:microsoft:azure_linux:prometheus-process-exporter, p-cpe:/a:microsoft:azure_linux:telegraf, p-cpe:/a:microsoft:azure_linux:azcopy, p-cpe:/a:microsoft:azure_linux:docker-cli

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

Exploit Ease: No known exploits are available

Patch Publication Date: 5/12/2026

Vulnerability Publication Date: 5/12/2026

Reference Information

CVE: CVE-2026-39821

Detections

Analytics