What’s Vulnerable › Vulnerabilities

CVE-2023-27321: OPC Foundation UA .NET Standard ConditionRefresh Resource Exhaustion Denial-of-Service Vulnerability

• Severity: high (CVSS 7.5 v3.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.0% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2024-05-07 · updated 2026-06-17
• Weakness: CWE-400

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.

Affected products

• Opcfoundation Ua-.Netstandard: before 1.4.371.86 — fixed in 1.4.371.86

How to fix

Upgrade to a fixed version: Opcfoundation Ua-.Netstandard 1.4.371.86. Check the vendor advisory for mitigations.

References

• https://files.opcfoundation.org/SecurityBulletins/OPC%20Foundation%20Security%20Bulletin%20CVE-2023-27321.pdf
• https://www.zerodayinitiative.com/advisories/ZDI-23-548/
• https://files.opcfoundation.org/SecurityBulletins/OPC%20Foundation%20Security%20Bulletin%20CVE-2023-27321.pdf
• https://www.zerodayinitiative.com/advisories/ZDI-23-548/

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