# CVE-2026-11420: Path Traversal in Altium Enterprise Server NIS Allows Unauthenticated Arbitrary File Write and File Read

> Unauthenticated attackers can exploit path traversal in Altium Enterprise Server to write arbitrary files and read archives, potentially achieving remote code execution.

- **Severity:** Critical 10.0 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 5 Jun 2026
- **Updated:** 5 Jun 2026
- **Also known as:** GHSA-q58x-mgvc-jhw9

## What is CVE-2026-11420?

CVE-2026-11420 is a critical path traversal vulnerability in Altium Enterprise Server, published on 5 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Two path traversal vulnerabilities in the Network Installation Service (NIS) of Altium Enterprise Server allow an unauthenticated network attacker to write arbitrary files to any writable location on the server filesystem and to read package archive files from the server. No authentication, session, or credentials are required.

Because content-controlled files can be written to web-accessible directories, or used to overwrite application binaries or configuration files, exploitation can be escalated to remote code execution in the context of the service account, and can disclose deployment package contents. Altium 365 cloud deployments are not affected, as the Network Installation Service is not part of the cloud offering.

Weakness: CWE-306 (Missing Authentication for Critical Functionality), CWE-22 (Improper Limitation of a Pathname to a Restricted Directory)

## Which versions are affected by CVE-2026-11420?

It affects 1 product.


Products: Altium On-Prem Enterprise Server.

## How do I fix CVE-2026-11420?

No fix has been published for CVE-2026-11420 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-11420 being exploited?

There is no known exploitation of CVE-2026-11420 in the wild and no public exploit code.

## Other vulnerabilities in Altium Enterprise Server

- [CVE-2026-11414](https://insights.sbomify.com/CVE-2026-11414/): Hardcoded credentials in Altium Enterprise Server (critical 10.0)
- [CVE-2026-11419](https://insights.sbomify.com/CVE-2026-11419/): Path Traversal in Altium Enterprise Server Vault UploadController Allows Arbitrary File Write (critical 9.4)
- [CVE-2025-27378](https://insights.sbomify.com/CVE-2025-27378/): SQL Injection in AES Due to Inactive SQL Parsing Configuration (high 8.6)
- [CVE-2026-1010](https://insights.sbomify.com/CVE-2026-1010/): Stored Cross-Site Scripting in Altium Enterprise Server Workflow Engine Allows Privilege Escalation (high 8.0)
- [CVE-2025-27380](https://insights.sbomify.com/CVE-2025-27380/): HTML Injection Leading to Script Execution in Altium Enterprise Server (high 7.6)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-11420 and fix it if it is affected.

What it is: CVE-2026-11420 is a critical path traversal vulnerability in Altium Enterprise Server, published on 5 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-11420 in the wild and no public exploit code.

Affected product: Altium Enterprise Server. 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-2026-11420/ (Markdown: https://insights.sbomify.com/CVE-2026-11420/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-11420
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-11420
- OSV: https://osv.dev/vulnerability/CVE-2026-11420

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-11420/
Summaries are generated and may contain mistakes; the official description above is the record.