CVE-2026-40701: F5 Dos

Medium severity, CVSS 4.8. EPSS: 0.7% chance of exploitation in the next 30 days.

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, up to and including 4.7.0; version 4.8.0 only
• F5 Nginx Gateway Fabric: from 1.3.0, up to and including 1.6.2; from 2.0.0, up to and including 2.6.0
• F5 Nginx Ingress Controller: from 3.5.0, up to and including 3.7.2; from 4.0.0, up to and including 4.0.1; from 5.0.0, up to and including 5.4.2
• F5 Nginx Instance Manager: from 2.16.0, up to and including 2.22.0
• F5 Nginx Open Source: from 1.19.0, up to and including 1.30.0
• F5 Nginx Plus: from r32, up to and including r36
• F5 Waf: from 4.9.0, up to and including 4.16.0; from 5.1.0, up to and including 5.8.0; from 5.9.0, up to and including 5.12.1

Published 2026-05-13. Last modified 2026-06-23.