CVE-2026-28753

A flaw was found in NGINX Plus and NGINX Open Source, specifically within the ngx_mail_smtp_module. This vulnerability allows an attacker-controlled DNS (Domain Name System) server to inject arbitrary headers into SMTP (Simple Mail Transfer Protocol) upstream requests. This is due to the improper handling of Carriage Return (CRLF) sequences in DNS responses. The primary consequence is the potential manipulation of these requests, which could alter their intended behavior.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.