# CVE-2026-44246: nnU-Net: Agentic workflow injection in `.github/workflows/issue-triage.yml` of `MIC-DKFZ/nnUNet`

> Attackers can inject malicious prompts into GitHub Actions workflows via issue content, leading to unauthorized code execution and privilege escalation.

- **Severity:** High 7.2 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 12 May 2026
- **Updated:** 13 May 2026
- **Also known as:** GHSA-63mx-j37w-gh59

## What is CVE-2026-44246?

CVE-2026-44246 is a high-severity code injection vulnerability in MIC-DKFZ nnUNet, published on 12 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

nnU-Net is a semantic segmentation framework that automatically adapts its pipeline to a dataset. Prior to 2.4.1, the nnU-Net Issue Triage workflow in .github/workflows/issue-triage.yml is vulnerable to Agentic Workflow Injection. The workflow sets allowed_non_write_users: ${{ github.event.issue.user.login }}, which means any logged-in GitHub user who opens an issue can reach this agentic workflow with attacker-controlled content. Untrusted issue title and body content are embedded directly into the prompt of anthropics/claude-code-action, and the workflow then runs a command-capable Claude agent with permission to comment on and relabel the current issue via gh. Because this workflow is triggered automatically on issues.opened, an external attacker can submit a crafted issue that steers the agent beyond its intended issue-triage purpose and influences authenticated issue actions. This vulnerability is fixed in 2.4.1.

Weakness: CWE-74 (Improper Neutralization of Special Elements in Output Used by a Downstream Component), CWE-1427 (Improper Neutralization of Input Used for LLM Prompting)

## Which versions are affected by CVE-2026-44246?

It affects 1 product.


Products: Dkfz Nnu-Net.

## How do I fix CVE-2026-44246?

No fix has been published for CVE-2026-44246 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-44246 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-44246 exists.

Public exploit code:

- Authorized security-research lab reproducing CVE-2026-44246 (GHSA-63mx-j37w-gh59): prompt injection via verbatim issue title/body inlining into the claude-code-action triage agent in nnU-Net's issue-triage workflow. Snapshot of MIC-DKFZ/nnUNet @ 9a1db0dd1c74894fa17e79014be4097f546a51be. (github_poc): https://github.com/pvharmo2/gha-lab-733c168b88
- Reproducible vulnerable/fixed fixtures for agentic workflow injection in GitHub Actions (CVE-2026-44246), plus measured detector coverage (github_poc): https://github.com/sushant-me/agentic-workflow-injection

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-44246 and fix it if it is affected.

What it is: CVE-2026-44246 is a high-severity code injection vulnerability in MIC-DKFZ nnUNet, published on 12 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-44246 exists.

Affected product: MIC-DKFZ nnUNet. 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-2026-44246/ (Markdown: https://insights.sbomify.com/CVE-2026-44246/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-44246
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-44246
- OSV: https://osv.dev/vulnerability/CVE-2026-44246

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-44246/
Summaries are generated and may contain mistakes; the official description above is the record.