CVE-2026-56434

EUVD-2026-44684
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.
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
f5CNA
6.5 MEDIUM
NETWORK
HIGH
NONE
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H
Base Score
CVSS 3.x
EPSS Score
Percentile: Unknown
Early Detection
Affected products identified ahead of NVD analysis through intelligence sources.
VendorProductVersionSource
f5nginx_plus
37.0.0.1 ≤
𝑥
< 37.0.3.1
CNA
f5nginx_plus
1.31.2 ≤
𝑥
< 1.31.3
CNA
f5nginx_plus
0.8.11 ≤
𝑥
< 1.30.4
CNA