# CVE-2021-25742: Ingress-nginx custom snippets allows retrieval of ingress-nginx serviceaccount token and secrets across all namespaces

> Users with ingress creation rights can exploit custom snippets to read all cluster secrets, requiring ingress-nginx updates.

- **Severity:** High 7.6 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:L`)
- **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:** 29 Oct 2021
- **Updated:** 16 Sep 2024
- **Also known as:** GHSA-4pp2-3663-mcw8, openSUSE-SU-2024:11726-1

## What is CVE-2021-25742?

CVE-2021-25742 is a high-severity missing authorization vulnerability in Kubernetes ingress-nginx, published on 29 Oct 2021. 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 user that can create or update ingress objects can use the custom snippets feature to obtain all secrets in the cluster.

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2021-25742?

It affects 2 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `rke` | openSUSE:Tumbleweed | All versions | 1.3.3-1.1 |

Products: Kubernetes Ingress-Nginx, Netapp Trident.

## How do I fix CVE-2021-25742?

Apply the vendor's patch.

## Is CVE-2021-25742 being exploited?

There is no known exploitation of CVE-2021-25742 in the wild and no public exploit code.

## Other vulnerabilities in Kubernetes ingress-nginx

- [CVE-2026-3288](https://insights.sbomify.com/CVE-2026-3288/): ingress-nginx rewrite-target nginx configuration injection (high 8.8)
- [CVE-2022-4886](https://insights.sbomify.com/CVE-2022-4886/): Ingress-nginx `path` sanitization can be bypassed with `log_format` directive (high 8.8)
- [CVE-2023-5043](https://insights.sbomify.com/CVE-2023-5043/): Ingress nginx annotation injection causes arbitrary command execution (high 7.6)
- [CVE-2023-5044](https://insights.sbomify.com/CVE-2023-5044/): Code injection via nginx.ingress.kubernetes.io/permanent-redirect annotation (high 7.6)
- [CVE-2021-25748](https://insights.sbomify.com/CVE-2021-25748/): Ingress-nginx `path` sanitization can be bypassed with newline character (high 7.6)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-25742 and fix it if it is affected.

What it is: CVE-2021-25742 is a high-severity missing authorization vulnerability in Kubernetes ingress-nginx, published on 29 Oct 2021. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-25742 in the wild and no public exploit code.

Affected product: Kubernetes ingress-nginx. 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-2021-25742/ (Markdown: https://insights.sbomify.com/CVE-2021-25742/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-25742
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-25742
- OSV: https://osv.dev/vulnerability/CVE-2021-25742

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-25742/
Summaries are generated and may contain mistakes; the official description above is the record.