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.

Attack Vector Network

Attack Complexity High

Privileges Required None

Attack Requirements Present

User Interaction None

Vulnerable System Confidentiality Impact None

Vulnerable System Integrity Impact Low

Vulnerable System Availability Impact None

Subsequent System Confidentiality Impact None

Subsequent System Integrity Impact None

Subsequent System Availability Impact None

Attack Vector Network

Attack Complexity High

Privileges Required None

Scope Unchanged

Confidentiality Impact None

Integrity Impact Low

Availability Impact None

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

No EPSS score available.

Exploitation none

Automatable no

Technical Impact partial

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions
F5 NGINX Open Source unknown
Version Status Constraints
1.29.0 affected < 1.29.7
0.6.27 affected < 1.28.3
F5 NGINX Plus unknown
Version Status Constraints
R36 affected < R36 P3
R35 affected < R35 P2
R34 affected < *
R33 affected < *
R32 affected < R32 P5

No data.

No data.

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Project Subscriptions

No data.

Advisories

No advisories yet.

Fixes

Solution

No solution given by the vendor.

Workaround

No workaround given by the vendor.

References
Link Providers
https://my.f5.com/manage/s/article/K000160367 cve-icon cve-icon
History

Tue, 24 Mar 2026 16:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Tue, 24 Mar 2026 15:15:00 +0000

Type Values Removed Values Added
Description NGINX Plus and NGINX Open Source have a vulnerability in the ngx_mail_smtp_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. 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.

Tue, 24 Mar 2026 14:45:00 +0000

Type Values Removed Values Added
Description NGINX Plus and NGINX Open Source have a vulnerability in the ngx_mail_smtp_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.
Title NGINX ngx_mail_proxy_module vulnerability
Weaknesses CWE-93
References
Metrics cvssV3_1

{'score': 3.7, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N'}

cvssV4_0

{'score': 6.3, 'vector': 'CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N'}

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: f5

Published:

Updated: 2026-03-24T15:24:34.995Z

Reserved: 2026-03-18T16:06:38.435Z

Link: CVE-2026-28753

cve-icon Vulnrichment

Updated: 2026-03-24T15:24:31.847Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-03-24T15:16:33.560

Modified: 2026-03-24T15:53:48.067

Link: CVE-2026-28753

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.

Weaknesses