PT-2021-20566 · 3S Smart Software Solutions · Codesys V2 Web-Server

Tenable Research · Published 2021-10-26 · Updated 2025-08-15 · CVE-2021-34585

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 web server versions prior to V1.1.9.22

Description: The issue arises when crafted web server requests trigger a parser error in the CODESYS V2 web server. Since the parser result is not checked under all conditions, a pointer dereference with an invalid address can occur, leading to a denial of service situation.

Recommendations: For versions prior to V1.1.9.22, update to version V1.1.9.22 or later to resolve the issue. As a temporary workaround, consider restricting access to the web server to minimize the risk of exploitation.

Exploit

Fix

DoS

Unchecked Return Value

Weakness Enumeration

CWE-252

Related Identifiers

CVE-2021-34585

Affected Products

Codesys V2 Web-Server

References · 8

• 🔥 https://tenable.com/security/research/tra-2021-47 · Exploit
• https://nvd.nist.gov/vuln/detail/CVE-2021-34585 · Security Note
• https://customers.codesys.com/index.php?eID=dumpFile&t=f&f=16876&token=a3f1d937f95e7034879f4f2ea8e5a99b168256a7&download= · Vendor Advisory
• https://osv.dev/vulnerability/CVE-2021-34585 · Vendor Advisory
• https://t.me/cibsecurity/31196 · Telegram Post
• https://t.me/cvenotify/22952 · Telegram Post
• https://t.me/cvenotify/23152 · Telegram Post
• https://t.me/cveNotify/132531 · Telegram Post