# CVE-2026-104939: NGINX Ingress Controller vulnerability

> Attackers can bypass external authentication to access protected paths in NGINX Ingress Controller when externalAuth is configured.

- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/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:** No
- **Published:** 14 Oct 2026
- **Updated:** 15 Oct 2026
- **Also known as:** GHSA-qcp7-h72p-6whw

## What is CVE-2026-104939?

CVE-2026-104939 is a high-severity authentication bypass vulnerability in F5 NGINX Ingress Controller, published on 14 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Description
NGINX Ingress Controller has a vulnerability when implementing an externalAuth policy for ingress. NGINX Ingress Controller may mishandle the HTTP response from an OAuth IdP and allow an attacker to acquire unauthenticated access to protected paths before the proper external authentication can happen.

Impact
This vulnerability may allow remote attackers 

unauthenticated

 access to protected 

paths. There is no control plane exposure; this is a data plane issue only.

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

Weakness: CWE-303 (Incorrect Implementation of Authentication Algorithm)

## Which versions are affected by CVE-2026-104939?


## How do I fix CVE-2026-104939?

No fix has been published for CVE-2026-104939 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-104939 being exploited?

There is no known exploitation of CVE-2026-104939 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-104939 and fix it if it is affected.

What it is: CVE-2026-104939 is a high-severity authentication bypass vulnerability in F5 NGINX Ingress Controller, published on 14 Oct 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-2026-104939 in the wild and no public exploit code.

Affected product: F5 NGINX Ingress Controller. 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-2026-104939/ (Markdown: https://insights.sbomify.com/CVE-2026-104939/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-104939
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-104939
- OSV: https://osv.dev/vulnerability/CVE-2026-104939

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-104939/
Summaries are generated and may contain mistakes; the official description above is the record.