# CVE-2026-40564: Apache Flink Kubernetes Operator: Server-Side Request Forgery and local file access in Kubernetes Operator

> Attackers with CR create permissions can exploit unvalidated URIs to read local files and access internal network resources via SSRF.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 26 May 2026
- **Updated:** 2 Jun 2026
- **Also known as:** GHSA-rj6x-mg28-wf4x

## What is CVE-2026-40564?

CVE-2026-40564 is a medium-severity server-side request forgery vulnerability in Apache Flink Kubernetes Operator, published on 26 May 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Files or Directories Accessible to External Parties, Server-Side Request Forgery (SSRF) vulnerability in Apache Flink Kubernetes Operator.

The FlinkSessionJob jarURI is currently not validated so that it points to user-owned files or addresses.  This lets a user with CR create permissions read files from the operator pod's filesystem and pull content from any backing store reachable through Flink's pluggable filesystem layer and access them through the submitted Flink job. Furthermore for fetching from http/https addresses there is currently no allowlist on the URI scheme, no host check, no IP-range restriction, and no protection against pointing the URI at internal or link-local addresses.This issue affects Apache Flink Kubernetes Operator: from 1.3.0 before 1.15.0.

Users are recommended to upgrade to version 1.15.0, which fixes the issue.

Weakness: CWE-918 (Server-Side Request Forgery), CWE-552 (Files or Directories Accessible to External Parties)

## Which versions are affected by CVE-2026-40564?

It affects 1 product.


Products: Apache Flink Kubernetes Operator.

## How do I fix CVE-2026-40564?

No fix has been published for CVE-2026-40564 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-40564 being exploited?

There is no known exploitation of CVE-2026-40564 in the wild and no public exploit code.

Public exploit code:

- CVE-2026-40564: SSRF via FlinkSessionJob jarURI in apache/flink-kubernetes-operator. Self-contained reproducer that runs on a local kind cluster with one make command. (github_poc): https://github.com/oscerd/CVE-2026-40564

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-40564 and fix it if it is affected.

What it is: CVE-2026-40564 is a medium-severity server-side request forgery vulnerability in Apache Flink Kubernetes Operator, published on 26 May 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-2026-40564 in the wild and no public exploit code.

Affected product: Apache Flink Kubernetes Operator. 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-2026-40564/ (Markdown: https://insights.sbomify.com/CVE-2026-40564/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-40564
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-40564
- OSV: https://osv.dev/vulnerability/CVE-2026-40564

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-40564/
Summaries are generated and may contain mistakes; the official description above is the record.