CVE-2026-56434
NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_ssi_module module.
Impact
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.
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| F5 | Nginx Gateway Fabric | from 1.3.0 through 1.6.2 from 2.0.0 before 2.6.7 |
| 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 Versions 4.0.0, 4.0.1 |
| F5 | Nginx Plus | from 37.0.0.1 before 37.0.3.1 from r33 before r36 Version r36 |
| 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 |