HOMEVULNERABILITIESCVE-2023-27321
HIGH

CVE-2023-27321

CWE-400Published: May 7, 2024· Updated: Jun 17, 2026

7.5
CVSS v3.1

Official Description

OPC Foundation UA .NET Standard ConditionRefresh Resource Exhaustion Denial-of-Service Vulnerability. This vulnerability allows remote attackers to create a denial-of-service condition on affected installations of OPC Foundation UA .NET Standard. Authentication is not required to exploit this vulnerability.

The specific flaw exists within the handling of OPC UA ConditionRefresh requests. By sending a large number of requests, an attacker can consume all available resources on the server. An attacker can leverage this vulnerability to create a denial-of-service condition on the system. Was ZDI-CAN-20505.

NVD Source

Technical Analysis

CVE-2023-27321 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:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected Vendors & Products

opcfoundation1 product(s)
ua-.netstandard
Source: NVD CPE · 1 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://files.opcfoundation.org/SecurityBulletins/OPC%20Foundation%20Security%20Bulletin%20CVE-2023-27321.pdf
ADVISORYhttps://www.zerodayinitiative.com/advisories/ZDI-23-548/
ADVISORYhttps://files.opcfoundation.org/SecurityBulletins/OPC%20Foundation%20Security%20Bulletin%20CVE-2023-27321.pdf
ADVISORYhttps://www.zerodayinitiative.com/advisories/ZDI-23-548/

All References (4)

→
https://files.opcfoundation.org/SecurityBulletins/OPC%20Foundation%20Security%20Bulletin%20CVE-2023-27321.pdfVendor Advisory
→
https://www.zerodayinitiative.com/advisories/ZDI-23-548/Third Party Advisory
→
https://files.opcfoundation.org/SecurityBulletins/OPC%20Foundation%20Security%20Bulletin%20CVE-2023-27321.pdfVendor Advisory
→
https://www.zerodayinitiative.com/advisories/ZDI-23-548/Third Party Advisory

Quick Facts

CVE IDCVE-2023-27321
CVSS Score7.5 / 10
SeverityHIGH
WeaknessCWE-400
CISA KEVNo
Affected1 vendor(s)
PublishedMay 7, 2024

Related CVEs (CWE-400)

CVE-2023-30769
9.8
CVE-2025-24190
9.8
CVE-2019-2259
9.8
CVE-2018-11936
9.8
CVE-2025-43193
9.8
CVE-2025-24269
9.8

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2023-27321 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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