Low severity3.7NVD Advisory· Published Mar 24, 2026· Updated Jun 17, 2026

CVE-2026-28753

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.

Affected products

Nginx/NGINX Plusllm-fuzzy
Nginx/NGINX Open Sourcellm-fuzzy
F5, Inc./Nginx Plusllm-fuzzy2 versions
(expand)+ 1 more
- (no CPE)
- (no CPE)range: R36
osv-coords3 versions
pkg:bitnami/nginx pkg:bitnami/nginx-gateway pkg:rpm/opensuse/nginx&distro=openSUSE%20Tumbleweed
>= 0.6.27, < 1.28.3+ 2 more
- (no CPE)range: >= 0.6.27, < 1.28.3
- (no CPE)range: >= 0.6.27, < 1.28.3
- (no CPE)range: < 1.29.7-1.1

Patches

Vulnerability mechanics

References

my.f5.com/manage/s/article/K000160367nvdVendor Advisory

News mentions

No linked articles in our index yet.

Severity

LowCVSS v3.1

3.7/ 10

CVSS v46.3

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Attack vector: Network
Complexity: High
Privileges: None
User interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: Low
Availability: None

Vector

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

EPSS

Probability of exploitation in the next 30 days.

0.26%

VYPR risk score

Composite of severity, exploitation, and reach.

0.24low

cvss	0.240
epss	0.000
exploit	0.000
kev	0.000
patch	0.000
ransomware	0.000

Weaknesses

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

CVE ID

CVE-2026-28753

Credits

AV
Asim Viladi Oglu Manizada
reporter
BL
Bird Liu (Lanzhou University)
reporter
CW
Colin Warren
reporter
XL
Xiao Liu (Yunnan University)
reporter
YT
Yuan Tan (UC Riverside)
reporter