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Alibaba Cloud Linux 3 : 0263: python-idna (ALINUX3-SA-2026:0263)

medium Nessus Plugin ID 342081

Synopsis

The remote Alibaba Cloud Linux host is missing a security update.

Description

The remote Alibaba Cloud Linux 3 host has a package installed that is affected by a vulnerability as referenced in the ALINUX3-SA-2026:0263 advisory.

 Package updates are available for Alibaba Cloud Linux 3 that fix the following vulnerabilities:

 CVE-2026-45409:
 Internationalized Domain Names in Applications (IDNA) for Python provides support for Internationalized Domain Names in Applications (IDNA) and Unicode IDNA Compatibility Processing. In versions prior to 3.15, payloads such as `\u0660 * N` or `\u30fb * N + \u6f22` utilize the `valid_contexto` function prior to length rejection, and for high values of `N` will take a long time to process. This is the same issue as CVE-2024-3651, however the original remediation in 2024 was not a complete fix. A specially crafted argument to the `idna.encode()` function could consume significant resources. This may lead to a denial- of-service. Starting in version 3.14, the function rejects long inputs as soon as practicable prior to any further processing to minimize resource consumption. In version 3.15, this approach was extended to lesser used alternate functions (i.e. per-label conversions and codec support). A workaround is available. Domain names cannot exceed 253 characters in length. If this length limit is enforced prior to passing the domain to the `idna.encode()` function, it should no longer consume significant resources. This is triggered by arbitrarily large inputs that would not occur in normal usage, but may be passed to the library assuming there is no preliminary input validation by the higher-level application.

Tenable has extracted the preceding description block directly from the Alibaba Cloud Linux 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

Update the affected python3-idna package.

See Also

http://mirrors.aliyun.com/alinux/3/cve/alinux3-sa-20260263.xml

Plugin Details

Severity: Medium

ID: 342081

File Name: alinux3_sa_2026-0263.nasl

Version: 1.1

Type: Local

Published: 9/1/2026

Updated: 9/1/2026

Supported Sensors: Nessus

Risk Information

VPR

Risk Factor: Low

Score: 3.2

Percentile: 50.55

CVSS v2

Risk Factor: Medium

Base Score: 5

Temporal Score: 3.7

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

CVSS Score Source: CVE-2026-45409

CVSS v3

Risk Factor: Medium

Base Score: 5.3

Temporal Score: 4.6

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

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

CVSS v4

Risk Factor: Medium

Base Score: 6.9

Threat Score: 2.7

Threat Vector: CVSS:4.0/E:U

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

Vulnerability Information

CPE: cpe:/o:alibabacloud:alibaba_cloud_linux_3, p-cpe:/a:alibabacloud:alibaba_cloud_linux_3:python3-idna

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

Exploit Ease: No known exploits are available

Patch Publication Date: 8/28/2026

Vulnerability Publication Date: 5/19/2026

Reference Information

CVE: CVE-2026-45409