CVE-2026-40701: NGINX ngx_http_ssl_module vulnerability

Severity: medium (CVSS 4.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.7% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-05-13 · updated 2026-10-26
Weakness: CWE-416

Description

NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_ssl_module module when the ssl_verify_client directive is set to "on" or "optional," and the ssl_ocsp directive is set to "on" or the leaf parameters are configured with a resolver. With this configuration, an unauthenticated attacker can send requests along with conditions beyond its control that may cause a heap-use-after-free error in the NGINX worker process. This vulnerability may result in limited modification of data or the NGINX worker process restarting. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

Affected products

F5 Dos: from 4.3.0 through 4.7.0; 4.8.0
F5 NGINX Gateway Fabric: from 1.3.0 through 1.6.2; from 2.0.0 through 2.6.0
F5 NGINX Ingress Controller: from 3.5.0 through 3.7.2; from 4.0.0 through 4.0.1; from 5.0.0 through 5.4.2
F5 NGINX Instance Manager: from 2.16.0 through 2.22.0
F5 NGINX Open Source: from 1.19.0 through 1.30.0
F5 NGINX Plus: from r32 through r36
F5 Waf: from 4.9.0 through 4.16.0; from 5.1.0 through 5.8.0; from 5.9.0 through 5.12.1

References

https://my.f5.com/manage/s/article/K000161021

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