Linux Distros Unpatched Vulnerability : CVE-2026-28753

critical Nessus Plugin ID 303521

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Synopsis

The Linux/Unix host has one or more packages installed with a vulnerability that the vendor indicates will not be patched.

Description

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

- 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)

Note that Nessus relies on the presence of the package as reported by the vendor.

Solution

There is no known solution at this time.

Plugin Details

Severity: Critical

ID: 303521

File Name: unpatched_CVE_2026_28753.nasl

Version: 1.11

Type: Local

Agent: unix

Family: Misc.

Published: 3/25/2026

Updated: 5/18/2026

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

Risk Information

VPR

Risk Factor: Low

Score: 1.2

CVSS v2

Risk Factor: Medium

Base Score: 6.4

Temporal Score: 5.4

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

CVSS Score Source: CVE-2026-28753

CVSS v3

Risk Factor: Critical

Base Score: 9.1

Temporal Score: 8.3

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

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

Vulnerability Information

CPE: cpe:/o:redhat:enterprise_linux:8, cpe:/o:canonical:ubuntu_linux:18.04:-:lts, cpe:/o:canonical:ubuntu_linux:16.04:-:lts, cpe:/o:canonical:ubuntu_linux:20.04:-:lts, p-cpe:/a:redhat:enterprise_linux:nginx, p-cpe:/a:redhat:enterprise_linux:nginx-all-modules, p-cpe:/a:redhat:enterprise_linux:nginx-filesystem, p-cpe:/a:redhat:enterprise_linux:nginx-mod-http-image-filter, p-cpe:/a:redhat:enterprise_linux:nginx-mod-http-perl, p-cpe:/a:redhat:enterprise_linux:nginx-mod-http-xslt-filter, p-cpe:/a:redhat:enterprise_linux:nginx-mod-mail, p-cpe:/a:redhat:enterprise_linux:nginx-mod-stream, cpe:/o:centos:centos:8, p-cpe:/a:centos:centos:nginx, p-cpe:/a:centos:centos:nginx-all-modules, p-cpe:/a:centos:centos:nginx-filesystem, p-cpe:/a:centos:centos:nginx-mod-http-image-filter, p-cpe:/a:centos:centos:nginx-mod-http-perl, p-cpe:/a:centos:centos:nginx-mod-http-xslt-filter, p-cpe:/a:centos:centos:nginx-mod-mail, p-cpe:/a:centos:centos:nginx-mod-stream, p-cpe:/a:canonical:ubuntu_linux:nginx, cpe:/o:canonical:ubuntu_linux:14.04:-:lts, cpe:/o:redhat:enterprise_linux:9, p-cpe:/a:redhat:enterprise_linux:nginx-mod-devel, p-cpe:/a:redhat:enterprise_linux:nginx-core, p-cpe:/a:centos:centos:nginx-mod-devel, cpe:/o:redhat:enterprise_linux:10, p-cpe:/a:centos:centos:nginx-core

Required KB Items: Host/local_checks_enabled, Host/cpu, global_settings/vendor_unpatched, Host/OS/identifier

Exploit Ease: No known exploits are available

Vulnerability Publication Date: 3/24/2026

Reference Information

CVE: CVE-2026-28753

Detections

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