CVE Tools
Sign in

CVE-2021-34586

CODESYS V2 web server: crafted requests could trigger a null pointer dereference (DoS)

Published: Oct 26, 2021Updated: Aug 15, 2025 Sources: CVE List NVDCWE-476
7.5HIGH
NVD MITRE
EPSS Score
13.1%
Top 4.1%
CISA KEV
Not in KEV
Exploits
1 Known
Remediation
Patch Available
Self-Check
Not available

Description

In the CODESYS V2 web server prior to V1.1.9.22 crafted web server requests may cause a Null pointer dereference in the CODESYS web server and may result in a denial-of-service condition.

No summary for this CVE yet.

CVSS Vector Breakdown

AV:NAC:LPR:NUI:NS:UC:NI:NA:H
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:NConfidentiality
None
I:NIntegrity
None
A:HAvailability
High
Open in CVSS calculator →

Weaknesses

CWE-476

Affected Products

wago
commercial·DE
750-823 firmware
ICS / OT / IoT
750-829 firmware
ICS / OT / IoT
750-831 firmware
ICS / OT / IoT
750-832 firmware
ICS / OT / IoT
750-852 firmware
ICS / OT / IoT
750-862 firmware
ICS / OT / IoT
750-880 firmware
ICS / OT / IoT
750-881 firmware
ICS / OT / IoT
CODESYS
oss-project·DEaka codesys gmbh
CODESYS V2
ICS / OT / IoT
codesys
ICS / OT / IoT
and 19 more affected products View all →

Exploitability

1 exploit source identified

Exploit details including PoC links, Metasploit modules, and scanner templates are available after registration.

View exploit details
Official Patch Available
Is your org exposed to CVE-2021-34586?We can run the check for you — a free external exposure review, no install. Check my exposure

Attack Graph

Products CVE Techniques Tactics

Click technique nodes for MITRE ATT&CK details · drag to pan · Ctrl/⌘ + scroll to zoom, or go fullscreen.

MITRE ATT&CK

2 techniques
Impact
Initial Access
View detailed technique mapping

References

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

Unlock Complete Vulnerability Intelligence

Get the full picture for CVE-2021-34586 and every CVE in our database. Create a free account — no credit card required.

Create Free Account
Plain-language analysis
Impact assessment and exploitation scenario in plain English
Attack graph visualization
Interactive attack path and kill chain mapping
Exploit details & PoC links
ExploitDB, Metasploit, GitHub PoCs with direct links
Nuclei scanner templates
Ready-to-use vulnerability scanner templates
Full remediation guide
Patch instructions, workarounds, and compliance impact
Interactive AI chat
Ask questions about this vulnerability in natural language
Related vulnerabilities
Semantically similar CVEs and attack patterns
REST API & MCP access
Integrate vulnerability data into your workflows