HOMEVULNERABILITIESCVE-2021-34585
HIGH

CVE-2021-34585

CWE-252Published: October 26, 2021· Updated: Jun 17, 2026

7.5
CVSS v3.1

Official Description

In the CODESYS V2 web server prior to V1.1.9.22 crafted web server requests can trigger a parser error. Since the parser result is not checked under all conditions, a pointer dereference with an invalid address can occur. This leads to a denial of service situation.

NVD Source

Technical Analysis

CVE-2021-34585 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in availability disruption (denial of service), with a CVSS base score of 7.5.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorNetwork
Attack ComplexityLow
Privileges Req.None
User InteractionNone
ScopeUnchanged
Impact
ConfidentialityNone
IntegrityNone
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected Vendors & Products

codesys1 product(s)
codesys
wago54 product(s)
750-823 firmware750-823750-829 firmware750-829750-831 firmware750-831750-832 firmware750-832750-852 firmware750-852750-862 firmware750-862+42
Source: NVD CPE · 55 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

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

All References (4)

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

Quick Facts

CVE IDCVE-2021-34585
CVSS Score7.5 / 10
SeverityHIGH
WeaknessCWE-252
CISA KEVNo
Affected2 vendor(s)
PublishedOct 26, 2021

Related CVEs (CWE-252)

CVE-2007-3798
9.8
CVE-2021-26955
9.8
CVE-2010-0211
9.8
CVE-2021-38171
9.8
CVE-2019-15900
9.8
CVE-2022-25718
9.8

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2021-34585 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWATCH.COM. CVE data is provided under the NVD usage policy.
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