# CVE-2026-8711: NGINX JavaScript vulnerability

> An unauthenticated attacker can trigger a heap buffer overflow in NGINX JavaScript, potentially causing a service restart or remote code execution.

- **Severity:** Critical 9.2 (`CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/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:** 19 May 2026
- **Updated:** 21 May 2026
- **Also known as:** ALPINE-CVE-2026-8711, AZL-87117, BELL-CVE-2026-8711, DEBIAN-CVE-2026-8711, GHSA-pj32-6rxc-gcmq, UBUNTU-CVE-2026-8711, USN-8425-1

## What is CVE-2026-8711?

CVE-2026-8711 is a critical memory corruption vulnerability in F5 NGINX JavaScript, published on 19 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

NGINX JavaScript has a vulnerability when the js_fetch_proxy directive is configured with at least one client-controlled NGINX variable (for example, $http_*, $arg_*, $cookie_*) and a location invoking the ngx.fetch() operation from NGINX JavaScript. An unauthenticated attacker can exploit this vulnerability by sending crafted HTTP requests. This may cause a heap buffer overflow in the NGINX worker process leading to a restart. Additionally, attackers can execute code on systems with Address Space Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR. 

Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

Weakness: CWE-122 (Heap-based Buffer Overflow)

## Which versions are affected by CVE-2026-8711?

It affects 1 product.


Products: F5 Njs.

## How do I fix CVE-2026-8711?

Apply the vendor's patch.

## Is CVE-2026-8711 being exploited?

There is no known exploitation of CVE-2026-8711 in the wild and no public exploit code.

## Other vulnerabilities in F5 NGINX JavaScript

- [CVE-2020-19692](https://insights.sbomify.com/CVE-2020-19692/): Memory corruption in n/a (critical 9.8)
- [CVE-2020-19695](https://insights.sbomify.com/CVE-2020-19695/): Memory corruption in n/a (critical 9.8)
- [CVE-2022-43286](https://insights.sbomify.com/CVE-2022-43286/): Use after free in n/a (critical 9.8)
- [CVE-2022-29379](https://insights.sbomify.com/CVE-2022-29379/): Denial of service in n/a (critical 9.8)
- [CVE-2022-27007](https://insights.sbomify.com/CVE-2022-27007/): Use after free in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-8711 and fix it if it is affected.

What it is: CVE-2026-8711 is a critical memory corruption vulnerability in F5 NGINX JavaScript, published on 19 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-2026-8711 in the wild and no public exploit code.

Affected product: F5 NGINX JavaScript. No package-level version data is available, so check the vendor advisory linked from the reference page.

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-2026-8711/ (Markdown: https://insights.sbomify.com/CVE-2026-8711/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-8711
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-8711
- OSV: https://osv.dev/vulnerability/CVE-2026-8711

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-8711/
Summaries are generated and may contain mistakes; the official description above is the record.