nginx 0.6.27 < 1.28.3 / 1.29.x < 1.29.7 SMTP Upstream Injection

low Nessus Plugin ID 306671

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Synopsis

The remote web server is affected by a vulnerability.

Description

The installed version of nginx is 0.6.27 prior to 1.28.3, or 1.29.x prior to 1.29.7. It is, therefore, affected by the following issue :

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

Solution

Upgrade to nginx 1.28.3 / 1.29.7 or later.

Plugin Details

Severity: Low

ID: 306671

File Name: nginx_CVE-2026-28753.nasl

Version: 1.2

Type: Combined

Agent: unix

Family: Web Servers

Published: 4/16/2026

Updated: 4/17/2026

Configuration: Enable paranoid mode

Supported Sensors: Nessus Agent, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 5.2

CVSS v2

Risk Factor: Low

Base Score: 2.6

Temporal Score: 1.9

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

CVSS Score Source: CVE-2026-28753

CVSS v3

Risk Factor: Low

Base Score: 3.7

Temporal Score: 3.2

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

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

Vulnerability Information

CPE: cpe:/a:nginx:nginx

Required KB Items: Settings/ParanoidReport, installed_sw/nginx

Exploit Ease: No known exploits are available

Patch Publication Date: 3/24/2026

Vulnerability Publication Date: 3/24/2026

Reference Information

CVE: CVE-2026-28753

Detections

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