Home/CVE/NGINX Plus and NGINX Open Source have a vulnerability in the ngx_mail_smtp_module module due to the improper handling of
CVE

CVE-2026-28753

NGINX Plus and NGINX Open Source have a vulnerability in the ngx_mail_smtp_module module due to the improper handling of

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.

LOW · CVSS 3.7 EPSS 0.00031
Monitor
  • No active-exploitation, high-EPSS, or public-exploit signals - routine patching cadence
Sigma rules0 YARA rules0
⬡

Weakness Classification

CWE-93Improper Neutralization of CRLF Sequences ('CRLF Injection')
▤

Affected Products & Versions

4
f5 nginx plusall versions
f5 nginx open source>= 0.6.27 and <= 0.9.7
f5 nginx open source>= 1.0.0 and < 1.28.3
f5 nginx open source>= 1.29.0 and < 1.29.7
▣

Scoring & Timeline

3.7
LOW · CVSS v3.1 · f5sirt@f5.com
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD24 Mar 2026 · 03:16 PM
CVSS VectorCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
SSVC triage · cisa-vulnrichment
Exploitation
none
Automatable
no
Technical impact
partial
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
⚑

Vendor Advisories

6
usnUSN-8375-1
suse-csafSUSE-SU-2026:1953-1
suse-csafSUSE-SU-2026:1761-1
msrcCVE-2026-28753
suse-csafopenSUSE-SU-2026:10423-1
🔗

References & Sources

1
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://my.f5.com/manage/s/article/K000160367Vendor Advisory
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