Medium 6.5Published Jul 15, 2026

CVE-2026-56434NGINX ngx_http_ssi_module vulnerability

Updated under an hour ago (Oct 28, 2026, 2:40 AM ET)

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It affects F5 NGINX Plus and 4 other products. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Every CVE for F5 NGINX Plus

Exploited in the last 30 days

NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_ssi_module module. This vulnerability may exist when the Server-Side Includes (SSI), proxy_pass, and proxy_buffering off directives are configured. With this configuration, an unauthenticated attacker with man-in-the-middle (MITM) ability to control responses from an upstream server may be able to cause a use-after-free in the NGINX worker process. This issue may lead to limited modification of memory or a restart of the NGINX worker process. Impact: This vulnerability may allow remote attackers to have limited control to modify memory contents or restart the NGINX worker process. There is no control plane exposure; this is a data plane issue only. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

CVSS: 6.5 MEDIUM (v3.1, CNA)CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H
Weakness (CWE): CWE-416
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: f5
NVD analysis: Analyzed
Record last updated: Jul 15, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

F5 NGINX Plus f5:nginx_plus (from the name)	from 37.0.0.1 before 37.0.3.1; from R36 before R36 P7; from R33	CNA record
F5 NGINX Open Source f5:nginx_open_source (from the name)	from 1.31.2 before 1.31.3; from 0.8.11 before 1.30.4	CNA record
f5 nginx_gateway_fabric f5:nginx_gateway_fabric	from 1.3.0 through 1.6.2; from 2.0.0 before 2.6.7	NVD
f5 nginx_ingress_controller f5:nginx_ingress_controller	from 3.5.0 through 3.7.2; from 5.0.0 before 5.5.3; from 2026-lts-r1 before 2026-lts-r4; 4.0.0; 4.0.1	NVD
f5 nginx_plus f5:nginx_plus	from 37.0.0.1 before 37.0.3.1; from r33 before r36; r36; r36; r36; r36; r36; r36; and 1 more ranges	NVD
f5 waf f5:waf	from 4.11.0 through 4.16.0; from 5.2.0 through 5.8.0; from 5.9.0 before 5.13.4	NVD

References

References

https://my.f5.com/manage/s/article/K000162098	vendor-advisory, patch

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.