PT-2021-20569 · 3S Smart Software Solutions · Codesys V2 Runtime Toolkit

Gerhard Hechenberger + 1 · Published 2021-10-26 · Updated 2025-08-15 · CVE-2021-34593

Positive Technologies (AI Summary)

CVSS v3.1

7.5

High

Base vector

AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Name of the Vulnerable Software and Affected Versions: CODESYS V2 Runtime Toolkit 32 Bit full and PLCWinNT versions prior to V2.4.7.56

Description: The issue allows unauthenticated crafted invalid requests to result in several denial-of-service conditions. This can cause running PLC programs to be stopped, memory to be leaked, or further communication clients to be blocked from accessing the PLC.

Recommendations: For versions prior to V2.4.7.56, update to version V2.4.7.56 or later to resolve the issue. As a temporary workaround, consider restricting access to the system to minimize the risk of exploitation.

Exploit

Fix

DoS

Improper Handling of Exceptional Conditions

Weakness Enumeration

CWE-755

Related Identifiers

CVE-2021-34593

Affected Products

Codesys V2 Runtime Toolkit

References · 10

• 🔥 http://packetstormsecurity.com/files/165874/WAGO-750-8xxx-PLC-Denial-Of-Service-User-Enumeration.html · Exploit
• 🔥 http://packetstormsecurity.com/files/164716/CODESYS-2.4.7.0-Denial-Of-Service.html · Exploit
• https://osv.dev/vulnerability/CVE-2021-34593 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2021-34593 · Security Note
• https://customers.codesys.com/index.php?eID=dumpFile&t=f&f=16877&token=8faab0fc1e069f4edfca5d5aba8146139f67a175&download= · Vendor Advisory
• https://t.me/cvenotify/22820 · Telegram Post
• https://t.me/cibsecurity/31203 · Telegram Post
• https://t.me/defcon_news/88857 · Telegram Post
• https://t.me/cveNotify/132533 · Telegram Post
• http://seclists.org/fulldisclosure/2021/Oct/64 · Note