{"id":"CVE-2023-27321","aliases":["EUVD-2023-1630","GHSA-vpf7-r2fv-75m9"],"status":"published","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.","severity":{"version":"3.0","score":7.5,"vector":"CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-12","score":0.01047,"percentile":0.64675,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-400"],"published":"2023-05-05T02:19:39Z","modified":"2026-10-28T02:31:03Z","fixes":[{"ecosystem":"NuGet","package":"OPCFoundation.NetStandard.Opc.Ua.Server","fixed_in":["1.4.371.86"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"NuGet","package":"OPCFoundation.NetStandard.Opc.Ua.Server","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.4.371.86"}]}]},{"source":"osv","ecosystem":"NuGet","package":"OPCFoundation.NetStandard.Opc.Ua.Server","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.4.371.86"}]}],"versions":["1.4.363.104-preview","1.4.363.107","1.4.364.40","1.4.365-gfc341ee8c5","1.4.365.1-preview","1.4.365.10","1.4.365.2","1.4.365.23","1.4.365.48","1.4.366.31-preview","1.4.366.38","1.4.367.100","1.4.367.39","1.4.367.41","1.4.367.42","1.4.367.64-preview","1.4.367.75","1.4.367.95","1.4.368.27-preview","1.4.368.33","1.4.368.52-preview","1.4.368.53","1.4.368.58","1.4.369.30","1.4.370.1","1.4.370.12","1.4.370.9","1.4.371.41","1.4.371.50","1.4.371.60"]}],"products":[{"vendor":"opc foundation","product":"ua .net standard"},{"vendor":"opcfoundation","product":"ua-.netstandard"},{"vendor":"opcfoundation","product":"unified_architecture_.net-standard"}],"references":[{"url":"https://www.zerodayinitiative.com/advisories/ZDI-23-548/","tags":["x_research-advisory","x_transferred","Third Party Advisory","advisory"]},{"url":"https://files.opcfoundation.org/SecurityBulletins/OPC%20Foundation%20Security%20Bulletin%20CVE-2023-27321.pdf","tags":["vendor-advisory","x_transferred","Vendor Advisory","advisory","web"]},{"url":"https://github.com/OPCFoundation/UA-.NETStandard/security/advisories/GHSA-vpf7-r2fv-75m9","tags":["web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2023-27321","tags":["advisory"]},{"url":"https://www.zerodayinitiative.com/advisories/ZDI-23-548","tags":["web"]},{"url":"https://github.com/advisories/GHSA-vpf7-r2fv-75m9"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/27xxx/CVE-2023-27321.json","tags":["advisory"]},{"url":"https://github.com/OPCFoundation/UA-.NETStandard","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2023-27321","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.","status":"published","published":"2024-05-07T22:55:01.898Z","modified":"2024-08-02T12:09:43.438Z","cvss":[{"version":"3.0","score":7.5,"vector":"CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high","assessor":"cna"}],"cwes":["CWE-400"],"updated_at":"2026-11-02T14:35:26.63732Z"}],"euvd":[{"id":"EUVD-2023-1630","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.","status":"published","published":"2024-05-07T22:55:01Z","modified":"2024-08-02T12:09:43Z","cvss":[{"version":"3.0","score":7.5,"vector":"CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"updated_at":"2026-11-03T03:50:06.766939Z"}],"ghsa":[{"id":"GHSA-vpf7-r2fv-75m9","title":"Uncontrolled Resource Consumption in OPC UA .NET Standard Reference Server","description":"This security update resolves a vulnerability in the OPC UA .NET Standard Reference Server that allows\nremote attackers to send malicious requests that consume all memory available to the server.\n\nhttps://files.opcfoundation.org/SecurityBulletins/OPC%20Foundation%20Security%20Bulletin%20CVE-2023-27321.pdf","status":"published","published":"2023-05-05T02:19:39Z","modified":"2024-05-08T13:46:55Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"cwes":["CWE-400"],"updated_at":"2026-11-02T14:37:48.08826Z"}],"nvd":[{"id":"CVE-2023-27321","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.","status":"published","published":"2024-05-07T23:15:15.76Z","modified":"2026-06-17T05:44:47.17Z","cvss":[{"version":"3.0","score":7.5,"vector":"CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high","assessor":"secondary"}],"cwes":["CWE-400"],"updated_at":"2026-11-02T14:09:15.329996Z"}],"osv":[{"id":"CVE-2023-27321","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.","status":"published","published":"2024-05-07T22:55:01.898Z","modified":"2026-10-28T02:31:03.938310555Z","cvss":[{"version":"3.0","score":7.5,"vector":"CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"cwes":["CWE-400"],"updated_at":"2026-11-02T15:44:31.135751Z"},{"id":"GHSA-vpf7-r2fv-75m9","title":"Uncontrolled Resource Consumption in OPC UA .NET Standard Reference Server","description":"This security update resolves a vulnerability in the OPC UA .NET Standard Reference Server that allows\nremote attackers to send malicious requests that consume all memory available to the server.\n\nhttps://files.opcfoundation.org/SecurityBulletins/OPC%20Foundation%20Security%20Bulletin%20CVE-2023-27321.pdf","status":"published","published":"2023-05-05T02:19:39Z","modified":"2024-05-08T14:00:59.29364Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"cwes":["CWE-400"],"updated_at":"2026-11-02T15:46:57.694388Z"}]}}