{"id":"CVE-2017-0247","url":"https://www.cyber-defence.io/tools/cve/CVE-2017-0247","generatedAt":"2026-10-28T23:13:51.190Z","title":"A denial of service vulnerability exists when the ASP.NET Core fails to properly validate web requests.","description":"A denial of service vulnerability exists when the ASP.NET Core fails to properly validate web requests. NOTE: Microsoft has not commented on third-party claims that the issue is that the TextEncoder.EncodeCore function in the System.Text.Encodings.Web package in ASP.NET Core Mvc before 1.0.4 and 1.1.x before 1.1.3 allows remote attackers to cause a denial of service by leveraging failure to properly calculate the length of 4-byte characters in the Unicode Non-Character range.","published":"2017-05-12T14:29:04.000Z","lastModified":"2026-06-17T00:57:20.000Z","status":"Modified","sourceIdentifier":"secure@microsoft.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:H/A:N"},"cwe":["CWE-20"],"affected":["microsoft/asp.net model view controller","microsoft/microsoft.aspnetcore.mvc.abstractions","microsoft/microsoft.aspnetcore.mvc.apiexplorer","microsoft/microsoft.aspnetcore.mvc.cors","microsoft/microsoft.aspnetcore.mvc.dataannotations","microsoft/microsoft.aspnetcore.mvc.formatters.json","microsoft/microsoft.aspnetcore.mvc.formatters.xml","microsoft/microsoft.aspnetcore.mvc.localization","microsoft/microsoft.aspnetcore.mvc.razor","microsoft/microsoft.aspnetcore.mvc.razor.host","microsoft/microsoft.aspnetcore.mvc.taghelpers","microsoft/microsoft.aspnetcore.mvc.viewfeatures","microsoft/microsoft.aspnetcore.mvc.webapicompatshim","microsoft/system.net.http","microsoft/system.net.http.winhttphandler","microsoft/system.net.security","microsoft/system.net.websockets.client","microsoft/system.text.encodings.web"],"epss":{"score":0.16911,"percentile":0.97039,"date":"2026-10-27","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"urgent","text":"EPSS puts the probability of exploitation in the next 30 days at 16.9%, higher than 97% of all known CVEs. Patch or mitigate before the next change window."},"changes":[],"references":[{"url":"https://github.com/aspnet/Announcements/issues/239","tags":["Technical Description","Third Party Advisory"],"source":"secure@microsoft.com"},{"url":"https://technet.microsoft.com/en-us/library/security/4021279.aspx","tags":["Patch","Vendor Advisory"],"source":"secure@microsoft.com"},{"url":"https://www.sidertia.com/Home/Community/Blog/2017/05/18/ASPNET-Core-Unicode-Non-Char-Encoding-DoS","tags":["Exploit","Third Party Advisory"],"source":"secure@microsoft.com"},{"url":"https://github.com/aspnet/Announcements/issues/239","tags":["Technical Description","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://technet.microsoft.com/en-us/library/security/4021279.aspx","tags":["Patch","Vendor Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://www.sidertia.com/Home/Community/Blog/2017/05/18/ASPNET-Core-Unicode-Non-Char-Encoding-DoS","tags":["Exploit","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2017-0247","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."}