# CVE-2026-39911: Hashgraph Guardian 3.5.1 Unsandboxed JavaScript Execution RCE

> Authenticated users can execute arbitrary code via unsandboxed JavaScript, leading to credential theft and administrative token forgery.

- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA: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:** 9 Apr 2026
- **Updated:** 14 Jul 2026
- **Also known as:** GHSA-wf7f-q2xr-hrmh

## What is CVE-2026-39911?

CVE-2026-39911 is a high-severity code injection vulnerability in hashgraph guardian, published on 9 Apr 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Hashgraph Guardian through version 3.5.1, fixed in commit 45fbe2f, contains an unsandboxed JavaScript execution vulnerability in the Custom Logic policy block worker that allows authenticated Standard Registry users to execute arbitrary code by passing user-supplied JavaScript expressions directly to the Node.js Function() constructor without isolation. Attackers can import native Node.js modules to read arbitrary files from the container filesystem, access process environment variables containing sensitive credentials such as RSA private keys, JWT signing keys, and API tokens, and forge valid authentication tokens for any user including administrators.

Weakness: CWE-668 (Exposure of Resource to Wrong Sphere)

## Which versions are affected by CVE-2026-39911?

It affects 1 product.


Products: Hedera Guardian.

## How do I fix CVE-2026-39911?

No fix has been published for CVE-2026-39911 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-39911 being exploited?

There is no known exploitation of CVE-2026-39911 in the wild and no public exploit code.

## Other vulnerabilities in hashgraph guardian

- [CVE-2026-45248](https://insights.sbomify.com/CVE-2026-45248/): Hedera Guardian Authentication Bypass Information Disclosure (medium 6.9)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-39911 and fix it if it is affected.

What it is: CVE-2026-39911 is a high-severity code injection vulnerability in hashgraph guardian, published on 9 Apr 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-2026-39911 in the wild and no public exploit code.

Affected product: hashgraph guardian. 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-2026-39911/ (Markdown: https://insights.sbomify.com/CVE-2026-39911/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-39911
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-39911
- OSV: https://osv.dev/vulnerability/CVE-2026-39911

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-39911/
Summaries are generated and may contain mistakes; the official description above is the record.