Amazon Linux 2023 : nginx, nginx-all-modules, nginx-core (ALAS2023-2026-1540)

high Nessus Plugin ID 306218

Synopsis

The remote Amazon Linux 2023 host is missing a security update.

Description

It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2023-2026-1540 advisory.

When the ngx_mail_auth_http_module module is enabled on NGINX Plus or NGINX Open Source, undisclosed requests can cause worker processes to terminate. This issue may occur when (1) CRAM-MD5 or APOP authentication is enabled, and (2) the authentication server permits retry by returning the Auth-Wait response header. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated. (CVE-2026-27651)

NGINX Open Source and NGINX Plus have a vulnerability in the ngx_http_dav_module module that might allow an attacker to trigger a buffer overflow to the NGINX worker process; this vulnerability may result in termination of the NGINX worker process or modification of source or destination file names outside the document root. This issue affects NGINX Open Source and NGINX Plus when the configuration file uses DAV module MOVE or COPY methods, prefix location (nonregular expression location configuration), and alias directives. The integrity impact is constrained because the NGINX worker process user has low privileges and does not have access to the entire system. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated. (CVE-2026-27654)

The 32-bit implementation of NGINX Open Source has a vulnerability in the ngx_http_mp4_module module, which might allow an attacker to over-read or over-write NGINX worker memory resulting in its termination, using a specially crafted MP4 file. The issue only affects 32-bit NGINX Open Source if it is built with the ngx_http_mp4_module module and the mp4 directive is used in the configuration file. Additionally, the attack is possible only if an attacker can trigger the processing of a specially crafted MP4 file with the ngx_http_mp4_module module.

Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
(CVE-2026-27784)

NGINX Plus and NGINX Open Source have a vulnerability in the ngx_mail_smtp_module module due to the improper handling of CRLF sequences in DNS responses. This allows an attacker-controlled DNS server to inject arbitrary headers into SMTP upstream requests, leading to potential request manipulation. Note:
Software versions which have reached End of Technical Support (EoTS) are not evaluated. (CVE-2026-28753)

NGINX Plus and NGINX Open Source have a vulnerability in the ngx_stream_ssl_module module due to the improper handling of revoked certificates when configured with the ssl_verify_client on and ssl_ocsp on directives, allowing the TLS handshake to succeed even after an OCSP check identifies the certificate as revoked.

Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
(CVE-2026-28755)

NGINX Open Source and NGINX Plus have a vulnerability in the ngx_http_mp4_module module, which might allow an attacker to trigger a buffer over-read or over-write to the NGINX worker memory resulting in its termination or possibly code execution, using a specially crafted MP4 file. This issue affects NGINX Open Source and NGINX Plus if it is built with the ngx_http_mp4_module module and the mp4 directive is used in the configuration file. Additionally, the attack is possible only if an attacker can trigger the processing of a specially crafted MP4 file with the ngx_http_mp4_module module.

Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
(CVE-2026-32647)

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 'dnf update nginx --releasever 2023.11.20260413' or or 'dnf update --advisory ALAS2023-2026-1540 --releasever 2023.11.20260413' to update your system.

Plugin Details

Severity: High

ID: 306218

File Name: al2023_ALAS2023-2026-1540.nasl

Version: 1.1

Type: Local

Agent: unix

Family: Amazon Linux Local Security Checks

Published: 4/13/2026

Updated: 4/13/2026

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

Risk Information

VPR

Risk Factor: Medium

Score: 6.7

CVSS v2

Risk Factor: High

Base Score: 8.5

Temporal Score: 6.7

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

CVSS Score Source: CVE-2026-27654

CVSS v3

Risk Factor: Medium

Base Score: 5.4

Temporal Score: 4.9

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

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

CVSS Score Source: CVE-2026-28755

CVSS v4

Risk Factor: High

Base Score: 8.5

Threat Score: 7.1

Threat Vector: CVSS:4.0/E:P

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

CVSS Score Source: CVE-2026-27784

Vulnerability Information

CPE: p-cpe:/a:amazon:linux:nginx-core, p-cpe:/a:amazon:linux:nginx-mod-mail, p-cpe:/a:amazon:linux:nginx-debugsource, p-cpe:/a:amazon:linux:nginx-mod-http-xslt-filter-debuginfo, p-cpe:/a:amazon:linux:nginx-mod-http-xslt-filter, p-cpe:/a:amazon:linux:nginx-debuginfo, p-cpe:/a:amazon:linux:nginx-filesystem, p-cpe:/a:amazon:linux:nginx-mod-http-perl-debuginfo, p-cpe:/a:amazon:linux:nginx-core-debuginfo, p-cpe:/a:amazon:linux:nginx-mod-stream-debuginfo, p-cpe:/a:amazon:linux:nginx, p-cpe:/a:amazon:linux:nginx-mod-http-perl, p-cpe:/a:amazon:linux:nginx-mod-stream, p-cpe:/a:amazon:linux:nginx-mod-mail-debuginfo, p-cpe:/a:amazon:linux:nginx-all-modules, p-cpe:/a:amazon:linux:nginx-mod-devel, cpe:/o:amazon:linux:2023, p-cpe:/a:amazon:linux:nginx-mod-http-image-filter-debuginfo, p-cpe:/a:amazon:linux:nginx-mod-http-image-filter

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: 4/13/2026

Vulnerability Publication Date: 3/24/2026

Reference Information

CVE: CVE-2026-27651, CVE-2026-27654, CVE-2026-27784, CVE-2026-28753, CVE-2026-28755, CVE-2026-32647

IAVA: 2026-A-0280

Detections

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