CVE-2026-40701

MEDIUM LAB

NGINX Plus and NGINX Open Source - Use-After-Free in ngx_http_ssl_module

Title source: llm
STIX 2.1

Exploitation Summary

EIP tracks 1 public exploit for CVE-2026-40701. PoCs published by edgecases-PurpleHax.

AI-analyzed exploit summary This repository provides intentionally vulnerable Docker images for multiple nginx CVEs (CVE-2026-40701, CVE-2026-42934, CVE-2026-42945, CVE-2026-42946) to facilitate lab testing. It includes detailed configurations and explanations for each vulnerability but does not contain functional exploit code.

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.

Exploits (1)

nomisec WRITEUP
by edgecases-PurpleHax · poc
https://github.com/edgecases-PurpleHax/cve-images

This repository provides intentionally vulnerable Docker images for multiple nginx CVEs (CVE-2026-40701, CVE-2026-42934, CVE-2026-42945, CVE-2026-42946) to facilitate lab testing. It includes detailed configurations and explanations for each vulnerability but does not contain functional exploit code.

Classification
Writeup 95%
Attack Type
Other
Complexity
Moderate
Reliability
Theoretical
Target: nginx 1.30.0
No auth needed
Prerequisites: Docker environment · nginx 1.30.0 · specific configurations for each CVE
mistral-large-3 · analyzed May 29, 2026 Full analysis →

References (1)

Core 1
Core References
Vendor Advisory vendor-advisory patch
https://my.f5.com/manage/s/article/K000161021

Scores

CVSS v3 4.8
EPSS 0.0068
EPSS Percentile 47.9%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:L

CISA SSVC

Vulnrichment
Exploitation none
Automatable no
Technical Impact partial

Lab Environment

COMMUNITY
Community Lab
docker pull rwils83/nginx-vuln-base:1.30.0
docker pull ghcr.io/digininja/dvwa:latest

Details

CWE
CWE-416
Status published
Products (13)
f5/dos 4.8.0
f5/dos 4.3.0 - 4.7.0
F5/NGINX Open Source 1.19.0 - 1.30.1
F5/NGINX Open Source 1.31.0
F5/NGINX Plus R32 - R32 P6
F5/NGINX Plus R36 - R36 P4
F5/NGINX Plus R37
f5/nginx_gateway_fabric 1.3.0 - 1.6.2
f5/nginx_ingress_controller 3.5.0 - 3.7.2
f5/nginx_instance_manager 2.16.0 - 2.22.0
... and 3 more
Published May 13, 2026
Tracked Since May 13, 2026