# CVE-2026-40701: NGINX ngx_http_ssl_module vulnerability

> An unauthenticated attacker can trigger a heap-use-after-free in NGINX when specific SSL verification and OCSP settings are enabled, causing data modification or service restart.

- **Severity:** Medium 6.3 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:L/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 13 May 2026
- **Updated:** 13 May 2026
- **Also known as:** ALPINE-CVE-2026-40701, AZL-86850, BELL-CVE-2026-40701, BIT-nginx-2026-40701, BIT-nginx-gateway-2026-40701, DEBIAN-CVE-2026-40701, ECHO-cbfe-5521-46aa, GHSA-x88q-x2r7-vg3g, MINI-46qf-f9vw-4m46, MINI-c3w3-2qj4-8v23, MINI-qhm3-fr99-hfmw, MINI-v453-p2c9-mfcp, MINI-x6rw-q733-vwfh, UBUNTU-CVE-2026-40701

## What is CVE-2026-40701?

CVE-2026-40701 is a medium-severity use after free vulnerability in F5 NGINX Open Source, published on 13 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2026-40701?

2 open source packages ship an affected version, including nginx and nginx-gateway. It affects 7 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `nginx` | Bitnami | From 1.19.0 | 1.30.1 |
| `nginx-gateway` | Bitnami | From 1.19.0 | 1.30.1 |

Products: F5 Dos, F5 Nginx Gateway Fabric, F5 Nginx Ingress Controller, F5 Nginx Instance Manager, F5 Nginx Open Source, F5 Nginx Plus, F5 Waf.

## How do I fix CVE-2026-40701?

Upgrade nginx to 1.30.1 or later.

## Is CVE-2026-40701 being exploited?

There is no known exploitation of CVE-2026-40701 in the wild and no public exploit code.

Public exploit code:

- Intentionally-vulnerable nginx 1.30.0 CVE lab images (CVE-2026-40701/42934/42945/42946) for isolated security research. Lab use only. (github_poc): https://github.com/edgecases-PurpleHax/cve-images

## Other vulnerabilities in F5 NGINX Open Source

- [CVE-2026-42055](https://insights.sbomify.com/CVE-2026-42055/): NGINX ngx_http_proxy_v2_module and ngx_http_grpc_module vulnerability (critical 9.2)
- [CVE-2026-42945](https://insights.sbomify.com/CVE-2026-42945/): NGINX ngx_http_rewrite_module vulnerability (critical 9.2)
- [CVE-2026-42946](https://insights.sbomify.com/CVE-2026-42946/): NGINX ngx_http_scgi_module and ngx_http_uwsgi_module vulnerability (high 8.3)
- [CVE-2026-40460](https://insights.sbomify.com/CVE-2026-40460/): NGINX ngx_quic_module vulnerability (medium 6.9)
- [CVE-2026-48142](https://insights.sbomify.com/CVE-2026-48142/): NGINX ngx_http_charset_module vulnerability (medium 6.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-40701 and fix it if it is affected.

What it is: CVE-2026-40701 is a medium-severity use after free vulnerability in F5 NGINX Open Source, published on 13 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-40701 in the wild and no public exploit code.

Affected packages and fixed versions:
- nginx (Bitnami): affected from 1.19.0; fixed in 1.30.1
- nginx-gateway (Bitnami): affected from 1.19.0; fixed in 1.30.1

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-40701/ (Markdown: https://insights.sbomify.com/CVE-2026-40701/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-40701
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-40701
- OSV: https://osv.dev/vulnerability/CVE-2026-40701

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-40701/
Summaries are generated and may contain mistakes; the official description above is the record.