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Vulnerability record · CVE-2026-28753 · published 24 March 2026

CVE-2026-28753: F5 nginx plus vulnerability

F5 · Nginx Plus

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.

6.3 CVSS 4.0 Medium EPSS 0.27% · top 82.3% CWE-93 · CWE-93
6.3CVSS 4.0 base score
0.27%EPSS exploitation probability, 30 days
NoNot in CISA KEV
2Affected product versions listed by NVD
1References
17 Jun 2026Last modified by 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.

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:

Affected products

2 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://my.f5.com/manage/s/article/K000160367 Vendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

7.5CVE-2023-44487HTTP/2 Rapid Reset stream cancellation denial of serviceThe HTTP/2 protocol permits a client to cancel many streams quickly, and the server's handling of those resets consumes disproportionate resources. T…KEVEPSS 100%analysed9.2CVE-2026-42533F5 nginx gateway fabric heap-based buffer overflow vulnerabilityA vulnerability exists in NGINX Plus and NGINX Open Source when a map directive uses regex matching and a string expression references the map's rege…EPSS 0.89%9.2CVE-2026-42055F5 dos heap-based buffer overflow vulnerabilityNGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_proxy_v2_module and ngx_http_grpc_module modules. This vulnerability exists whe…EPSS 2.4%9.2CVE-2026-42530F5 nginx gateway fabric use after free vulnerabilityNGINX Open Source has a vulnerability in the ngx_http_v3_module module. When NGINX Open Source is configured to use the HTTP/3 QUIC module, a remote …EPSS 1.1%9.2CVE-2026-9256F5 nginx open source heap-based buffer overflow vulnerabilityNGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_rewrite_module module. This vulnerability exists when a rewrite directive uses …EPSS 2.7%9.2CVE-2026-42945NGINX rewrite module heap buffer overflow via crafted HTTP requestsNGINX Plus and NGINX Open Source contain a heap buffer overflow in the ngx_http_rewrite_module when a rewrite directive is followed by another rewrit…EPSS 3.4%analysed8.8CVE-2026-60005F5 nginx gateway fabric use of uninitialized resource vulnerabilityNGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_slice_module module. When the slice directive and unnamed regex captures are co…EPSS 0.53%8.8CVE-2026-27654F5 nginx plus heap-based buffer overflow vulnerabilityNGINX Open Source and NGINX Plus have a vulnerability in the ngx_http_dav_module module that might allow an attacker to trigger a buffer overflow to …EPSS 1.5%

Source: NIST National Vulnerability Database (record CVE-2026-28753), CISA KEV, FIRST EPSS (scores of 2026-09-28). This page is refreshed as NVD updates the record.