CRLF injection in NGINX Open Source and NGINX Plus - CVE-2026-28753
Published: March 25, 2026
Vulnerability identifier: #VU124482
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N/E:U/U:Green
CVE-ID: CVE-2026-28753
CWE-ID: CWE-93
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: F5 Networks
Affected software:
NGINX Open Source
NGINX Plus
NGINX Open Source
NGINX Plus
Detailed vulnerability description
The vulnerability allows a remote attacker to inject arbitrary data in server response.
The vulnerability exists due to insufficient validation of attacker-supplied data in the ngx_mail_smtp_module module when handling DNS responses. A remote attacker can inject arbitrary headers into SMTP upstream requests and manipulate data.
How to mitigate CVE-2026-28753
Install updates from vendor's website.