{"id":"CVE-2023-27321","url":"https://www.cyber-defence.io/tools/cve/CVE-2023-27321","generatedAt":"2026-10-24T11:08:30.363Z","title":"OPC Foundation UA .NET Standard ConditionRefresh Resource Exhaustion Denial-of-Service Vulnerability.","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.\n\nThe 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.","published":"2024-05-07T23:15:16.000Z","lastModified":"2026-06-17T05:44:47.000Z","status":"Analyzed","sourceIdentifier":"zdi-disclosures@trendmicro.com","cvss":{"version":"3.0","score":7.5,"severity":"HIGH","vector":"CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},"cwe":["CWE-400"],"affected":["opcfoundation/ua-.netstandard"],"epss":{"score":0.01047,"percentile":0.63923,"date":"2026-10-23","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"high","text":"High impact if exploited, but EPSS currently rates exploitation as unlikely (1.05%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit."},"changes":[],"references":[{"url":"https://files.opcfoundation.org/SecurityBulletins/OPC%20Foundation%20Security%20Bulletin%20CVE-2023-27321.pdf","tags":["Vendor Advisory"],"source":"zdi-disclosures@trendmicro.com"},{"url":"https://www.zerodayinitiative.com/advisories/ZDI-23-548/","tags":["Third Party Advisory"],"source":"zdi-disclosures@trendmicro.com"},{"url":"https://files.opcfoundation.org/SecurityBulletins/OPC%20Foundation%20Security%20Bulletin%20CVE-2023-27321.pdf","tags":["Vendor Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://www.zerodayinitiative.com/advisories/ZDI-23-548/","tags":["Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2023-27321","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}