# CVE-2026-6807: NSA GRASSMARLIN Improper Restriction of XML External Entity Reference

> Crafted session data triggers improper XML handling in NSA GRASSMARLIN, potentially exposing sensitive information to attackers.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/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:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 28 Apr 2026
- **Updated:** 29 Apr 2026
- **Also known as:** GHSA-w2pw-52qg-478g

## What is CVE-2026-6807?

CVE-2026-6807 is a medium-severity vulnerability in NSA GRASSMARLIN, published on 28 Apr 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A vulnerability in GRASSMARLIN v3.2.1 allows crafted session data to 
trigger improper handling of XML input, which may result in unintended 
exposure of sensitive information. The flaw stems from insufficient 
hardening of the XML parsing process.

Weakness: CWE-611 (Improper Restriction of XML External Entity Reference)

## Which versions are affected by CVE-2026-6807?


## How do I fix CVE-2026-6807?

No fix has been published for CVE-2026-6807 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-6807 being exploited?

There is no known exploitation of CVE-2026-6807 in the wild and no public exploit code.

Public exploit code:

- Reverse Engineered based on CISA disclosure of new CVE (github_poc): https://github.com/SecTestAnnaQuinn/Grassmarlin-CVE-2026-6807-XXE-POC

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-6807 and fix it if it is affected.

What it is: CVE-2026-6807 is a medium-severity vulnerability in NSA GRASSMARLIN, published on 28 Apr 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-6807 in the wild and no public exploit code.

Affected product: NSA GRASSMARLIN. 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-2026-6807/ (Markdown: https://insights.sbomify.com/CVE-2026-6807/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-6807
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-6807
- OSV: https://osv.dev/vulnerability/CVE-2026-6807

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-6807/
Summaries are generated and may contain mistakes; the official description above is the record.