Amazon Linux 2 : python-jwcrypto, --advisory ALAS2-2026-3254 (ALAS-2026-3254)

medium Nessus Plugin ID 311204

Synopsis

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

Description

The version of python-jwcrypto installed on the remote host is prior to 0.4.2-1. It is, therefore, affected by a vulnerability as referenced in the ALAS2-2026-3254 advisory.

JWCrypto implements JWK, JWS, and JWE specifications using python-cryptography. Prior to 1.5.7, an unauthenticated attacker can exhaust server memory by sending crafted JWE tokens with ZIP compression. The existing patch for CVE-2024-28102 limits input token size to 250KB but does not validate the decompressed output size. An unauthenticated attacker can cause memory exhaustion on memory-constrained systems. A token under the 250KB input limit can decompress to approximately 100MB. This vulnerability is fixed in 1.5.7. (CVE-2026-39373)

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 python-jwcrypto' or or 'yum update --advisory ALAS2-2026-3254' to update your system.

Plugin Details

Severity: Medium

ID: 311204

File Name: al2_ALAS-2026-3254.nasl

Version: 1.1

Type: Local

Agent: unix

Family: Amazon Linux Local Security Checks

Published: 4/30/2026

Updated: 4/30/2026

Supported Sensors: Nessus Agent, Continuous Assessment, Nessus

Risk Information

VPR

Risk Factor: Low

Score: 2.2

CVSS v2

Risk Factor: Medium

Base Score: 5

Temporal Score: 3.9

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

CVSS Score Source: CVE-2026-39373

CVSS v3

Risk Factor: Medium

Base Score: 5.3

Temporal Score: 4.8

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:P/RL:O/RC:C

Vulnerability Information

CPE: cpe:/o:amazon:linux:2, p-cpe:/a:amazon:linux:python-jwcrypto

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

Exploit Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 4/30/2026

Vulnerability Publication Date: 4/7/2026

Reference Information

CVE: CVE-2026-39373

Detections

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