Is CVE-2026-28753 in the CISA KEV catalog?

No. CVE-2026-28753 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-28753?

CVE-2026-28753 has a CVSS v3 base score of 3.7 (Moderate).

What is the EPSS score for CVE-2026-28753?

CVE-2026-28753 has an EPSS score of 0.26% (18th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2026-28753?

Upgrade nginx on debian 11 to 1.18.0-6.1+deb11u6 or later. Fixes are available for 29 affected products.

CVE & CISA-KEV Catalog

CVE-2026-28753

MEDIUM

3.7

CVSS v3

NVD

Description

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.

CWE-93

How to fix

Remediation Available

nginxDebian

Fixed in:1.18.0-6.1+deb11u6CVE-2026-28753

Fixed in:1.22.1-9+deb12u5CVE-2026-28753

Fixed in:1.26.3-3+deb13u3CVE-2026-28753

Fixed in:1.28.3-1CVE-2026-28753

nginxRocky

Fixed in:main@aarch64RHSA-2026:8346

Fixed in:main@srcRHSA-2026:8346

Fixed in:main@x86_64RHSA-2026:8346

Fixed in:main@noarchRHSA-2026:8346

nginxRed Hat / RHEL

Fixed in:main@x86_64RHSA-2026:8346

Fixed in:main@noarchRHSA-2026:8346

Fixed in:main@aarch64RHSA-2026:8346

Fixed in:main@srcRHSA-2026:8346

libnginx-mod-http-auth-pamUbuntu

Fixed in:1.14.0-0ubuntu1.11+esm2USN-8375-1

libnginx-mod-http-cache-purgeUbuntu

Fixed in:1.14.0-0ubuntu1.11+esm2USN-8375-1

libnginx-mod-http-dav-extUbuntu

Fixed in:1.14.0-0ubuntu1.11+esm2USN-8375-1

libnginx-mod-http-echoUbuntu

Fixed in:1.14.0-0ubuntu1.11+esm2USN-8375-1

libnginx-mod-http-fancyindexUbuntu

Fixed in:1.14.0-0ubuntu1.11+esm2USN-8375-1

libnginx-mod-http-geoipUbuntu

Fixed in:1.14.0-0ubuntu1.11+esm2USN-8375-1

libnginx-mod-http-headers-more-filterUbuntu

Fixed in:1.14.0-0ubuntu1.11+esm2USN-8375-1

Fixed in:1.18.0-0ubuntu1.7+esm1USN-8375-1

libnginx-mod-http-image-filterUbuntu

Fixed in:1.14.0-0ubuntu1.11+esm2USN-8375-1

libnginx-mod-http-luaUbuntu

Fixed in:1.14.0-0ubuntu1.11+esm2USN-8375-1

Fixed in:1.18.0-0ubuntu1.7+esm1USN-8375-1

libnginx-mod-http-ndkUbuntu

Fixed in:1.14.0-0ubuntu1.11+esm2USN-8375-1

libnginx-mod-http-perlUbuntu

Fixed in:1.14.0-0ubuntu1.11+esm2USN-8375-1

libnginx-mod-http-subs-filterUbuntu

Fixed in:1.14.0-0ubuntu1.11+esm2USN-8375-1

libnginx-mod-http-uploadprogressUbuntu

Fixed in:1.14.0-0ubuntu1.11+esm2USN-8375-1

libnginx-mod-http-upstream-fairUbuntu

Fixed in:1.14.0-0ubuntu1.11+esm2USN-8375-1

libnginx-mod-http-xslt-filterUbuntu

Fixed in:1.14.0-0ubuntu1.11+esm2USN-8375-1

libnginx-mod-mailUbuntu

Fixed in:1.14.0-0ubuntu1.11+esm2USN-8375-1

Fixed in:1.18.0-0ubuntu1.7+esm1USN-8375-1

libnginx-mod-nchanUbuntu

Fixed in:1.14.0-0ubuntu1.11+esm2USN-8375-1

Fixed in:1.18.0-0ubuntu1.7+esm1USN-8375-1

libnginx-mod-rtmpUbuntu

Fixed in:1.14.0-0ubuntu1.11+esm2USN-8375-1

Fixed in:1.18.0-0ubuntu1.7+esm1USN-8375-1

libnginx-mod-streamUbuntu

Fixed in:1.14.0-0ubuntu1.11+esm2USN-8375-1

nginxUbuntu

Fixed in:1.4.6-1ubuntu3.9+esm6USN-8375-1

Fixed in:1.10.3-0ubuntu0.16.04.5+esm7USN-8375-1

Fixed in:1.14.0-0ubuntu1.11+esm2USN-8375-1

Fixed in:1.18.0-0ubuntu1.7+esm1USN-8375-1

nginx-commonUbuntu

Fixed in:1.4.6-1ubuntu3.9+esm6USN-8375-1

nginx-coreUbuntu

Fixed in:1.4.6-1ubuntu3.9+esm6USN-8375-1

Fixed in:1.10.3-0ubuntu0.16.04.5+esm7USN-8375-1

Fixed in:1.14.0-0ubuntu1.11+esm2USN-8375-1

Fixed in:1.18.0-0ubuntu1.7+esm1USN-8375-1

nginx-extrasUbuntu

Fixed in:1.4.6-1ubuntu3.9+esm6USN-8375-1

Fixed in:1.10.3-0ubuntu0.16.04.5+esm7USN-8375-1

Fixed in:1.14.0-0ubuntu1.11+esm2USN-8375-1

Fixed in:1.18.0-0ubuntu1.7+esm1USN-8375-1

nginx-fullUbuntu

Fixed in:1.4.6-1ubuntu3.9+esm6USN-8375-1

Fixed in:1.10.3-0ubuntu0.16.04.5+esm7USN-8375-1

Fixed in:1.14.0-0ubuntu1.11+esm2USN-8375-1

Fixed in:1.18.0-0ubuntu1.7+esm1USN-8375-1

nginx-lightUbuntu

Fixed in:1.4.6-1ubuntu3.9+esm6USN-8375-1

Fixed in:1.10.3-0ubuntu0.16.04.5+esm7USN-8375-1

Fixed in:1.14.0-0ubuntu1.11+esm2USN-8375-1

Fixed in:1.18.0-0ubuntu1.7+esm1USN-8375-1

nginx-naxsiUbuntu

Fixed in:1.4.6-1ubuntu3.9+esm6USN-8375-1

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityHigh

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityLow

AvailabilityNone

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N

Exploit Intelligence

0.26%probability of exploitation in 30 days

18thpercentile

Low risk: more likely to be exploited than 18% of all known CVEs.

References

Vendor Advisory1

my.f5.com

Related Vulnerabilities

Other CWE-93 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2025-61884	High	7.5	98%	KEV + Ransom	-
CVE-2022-0666	High	7.5	44%	-	Fix
CVE-2016-3115	Medium	6.4	37%	-	Fix
CVE-2024-20337	High	8.2	30%	-	Fix
CVE-2021-39172	High	8.8	29%	-	Fix
CVE-2016-4975	Medium	6.1	20%	-	Fix

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-03-26.