CVE-2026-56434

HIGH CVSS 4.0: 8.3 EPSS 0.45%
Updated Aug 10, 2026
F5
Parameter Value
CVSS 8.3 (HIGH)
Affected Versions 1.3.0 — r36
Fixed In 2.6.7
Type CWE-416 (Use After Free)
Vendor F5
Public PoC No

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.

Attack Parameters

Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Attack Requirements
Present
Additional conditions required
Privileges Required
None
No privileges needed
User Interaction
None
No user interaction needed

Impact Assessment

Confidentiality
None
No data leak
Integrity
Low
Partial data modification
Availability
High
Complete denial of service

CVSS Vector v4.0

Weakness Type (CWE)

Vulnerable Products 19

Configuration From (including) Up to (excluding)
F5 Nginx_Gateway_Fabric
cpe:2.3:a:f5:nginx_gateway_fabric:*:*:*:*:*:*:*:*
1.3.0 <= 1.6.2
F5 Nginx_Gateway_Fabric
cpe:2.3:a:f5:nginx_gateway_fabric:*:*:*:*:*:*:*:*
2.0.0 2.6.7
F5 Nginx_Ingress_Controller
cpe:2.3:a:f5:nginx_ingress_controller:*:*:*:*:continuous_releases:*:*:*
3.5.0 <= 3.7.2
F5 Nginx_Ingress_Controller
cpe:2.3:a:f5:nginx_ingress_controller:*:*:*:*:continuous_releases:*:*:*
5.0.0 5.5.3
F5 Nginx_Ingress_Controller
cpe:2.3:a:f5:nginx_ingress_controller:*:*:*:*:long-term_support:*:*:*
2026-lts-r1 2026-lts-r4
F5 Nginx_Ingress_Controller
cpe:2.3:a:f5:nginx_ingress_controller:4.0.0:*:*:*:continuous_releases:*:*:*
F5 Nginx_Ingress_Controller
cpe:2.3:a:f5:nginx_ingress_controller:4.0.1:*:*:*:continuous_releases:*:*:*
F5 Nginx_Plus
cpe:2.3:a:f5:nginx_plus:*:*:*:*:*:*:*:*
37.0.0.1 37.0.3.1
F5 Nginx_Plus
cpe:2.3:a:f5:nginx_plus:*:*:*:*:*:*:*:*
r33 r36
F5 Nginx_Plus
cpe:2.3:a:f5:nginx_plus:r36:-:*:*:*:*:*:*
F5 Nginx_Plus
cpe:2.3:a:f5:nginx_plus:r36:p1:*:*:*:*:*:*
F5 Nginx_Plus
cpe:2.3:a:f5:nginx_plus:r36:p2:*:*:*:*:*:*
F5 Nginx_Plus
cpe:2.3:a:f5:nginx_plus:r36:p3:*:*:*:*:*:*
F5 Nginx_Plus
cpe:2.3:a:f5:nginx_plus:r36:p4:*:*:*:*:*:*
F5 Nginx_Plus
cpe:2.3:a:f5:nginx_plus:r36:p5:*:*:*:*:*:*
F5 Nginx_Plus
cpe:2.3:a:f5:nginx_plus:r36:p6:*:*:*:*:*:*
F5 Waf
cpe:2.3:a:f5:waf:*:*:*:*:*:nginx:*:*
4.11.0 <= 4.16.0
F5 Waf
cpe:2.3:a:f5:waf:*:*:*:*:*:nginx:*:*
5.2.0 <= 5.8.0
F5 Waf
cpe:2.3:a:f5:waf:*:*:*:*:*:nginx:*:*
5.9.0 5.13.4