# CVE-2026-4342: ingress-nginx comment-based nginx configuration injection

> Attackers can inject nginx configuration via Ingress annotations to execute arbitrary code and read cluster secrets in ingress-nginx.

- **Severity:** High 8.8 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 19 Mar 2026
- **Updated:** 21 Mar 2026
- **Also known as:** GHSA-f53h-mxv9-cp98, GO-2026-4796

## What is CVE-2026-4342?

CVE-2026-4342 is a high-severity code injection vulnerability in Kubernetes ingress-nginx, published on 19 Mar 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

A security issue was discovered in ingress-nginx where a combination of Ingress annotations can be used to inject configuration into nginx. This can lead to arbitrary code execution in the context of the ingress-nginx controller, and disclosure of Secrets accessible to the controller. (Note that in the default installation, the controller can access all Secrets cluster-wide.)

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2026-4342?

3 open source packages ship an affected version, including k8s.io/ingress-nginx. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `k8s.io/ingress-nginx` | Go | All versions | 0.0.0-20260319175635-5183b7d86137 |
| `k8s.io/ingress-nginx` | Go | All versions | 0.0.0-20260319175635-5183b7d86137 |
| `k8s.io/ingress-nginx` | Go | All versions | 0.0.0-20260319175635-5183b7d86137 |

Products: Kubernetes Nginx Ingress Controller.

## How do I fix CVE-2026-4342?

Upgrade k8s.io/ingress-nginx to 0.0.0-20260319175635-5183b7d86137 or later.

## Is CVE-2026-4342 being exploited?

There is no known exploitation of CVE-2026-4342 in the wild and no public exploit code.

Public exploit code:

- https://github.com/stuartMoorhouse/CVE-2026-4342 (github_poc): https://github.com/stuartMoorhouse/CVE-2026-4342

## Other vulnerabilities in Kubernetes ingress-nginx

- [CVE-2018-1002104](https://insights.sbomify.com/CVE-2018-1002104/): Kubernetes ingress exposes sensitive information (medium 5.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-4342 and fix it if it is affected.

What it is: CVE-2026-4342 is a high-severity code injection vulnerability in Kubernetes ingress-nginx, published on 19 Mar 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-4342 in the wild and no public exploit code.

Affected packages and fixed versions:
- k8s.io/ingress-nginx (Go): affected all versions; fixed in 0.0.0-20260319175635-5183b7d86137
- k8s.io/ingress-nginx (Go): affected all versions; fixed in 0.0.0-20260319175635-5183b7d86137
- k8s.io/ingress-nginx (Go): affected all versions; fixed in 0.0.0-20260319175635-5183b7d86137

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-2026-4342/ (Markdown: https://insights.sbomify.com/CVE-2026-4342/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-4342
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-4342
- OSV: https://osv.dev/vulnerability/CVE-2026-4342

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-4342/
Summaries are generated and may contain mistakes; the official description above is the record.