HIGH
CVE-2021-34586
CWE-476Published: 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 may cause a Null pointer dereference in the CODESYS web server and may result in a denial-of-service condition.
Technical Analysis
CVE-2021-34586 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
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
All References (4)
→
→
https://www.tenable.com/security/research/tra-2021-47Exploit · Third Party Advisory
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https://www.tenable.com/security/research/tra-2021-47Exploit · Third Party Advisory
Quick Facts
CVE IDCVE-2021-34586
CVSS Score7.5 / 10
SeverityHIGH
WeaknessCWE-476
CISA KEVNo
Affected2 vendor(s)
PublishedOct 26, 2021
Related CVEs (CWE-476)
Recommended Actions
- →Apply vendor patches immediately
- →Monitor CVE-2021-34586 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.