{"id":"CVE-2021-40344","url":"https://www.cyber-defence.io/tools/cve/CVE-2021-40344","generatedAt":"2026-11-05T00:59:06.136Z","title":"In the Custom Includes section of the Admin panel, an administrator can upload files with arbitrary extensions as long as the MIME type corresponds to an image.","description":"An issue was discovered in Nagios XI 5.8.5. In the Custom Includes section of the Admin panel, an administrator can upload files with arbitrary extensions as long as the MIME type corresponds to an image. Therefore it is possible to upload a crafted PHP script to achieve remote command execution.","published":"2021-10-26T11:15:08.000Z","lastModified":"2026-06-17T04:06:46.000Z","status":"Modified","sourceIdentifier":"cve@mitre.org","cvss":{"version":"3.1","score":7.2,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H"},"cwe":["CWE-434"],"affected":["nagios/nagios xi"],"epss":{"score":0.64804,"percentile":0.99246,"date":"2026-11-03","history":[{"date":"2026-09-20","score":0.64804,"percentile":0.99207}]},"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 64.8%, higher than 99% of all known CVEs. Patch or mitigate before the next change window."},"changes":[],"references":[{"url":"https://assets.nagios.com/downloads/nagiosxi/CHANGES-5.TXT","tags":["Release Notes","Vendor Advisory"],"source":"cve@mitre.org"},{"url":"https://synacktiv.com","tags":["Not Applicable"],"source":"cve@mitre.org"},{"url":"https://www.synacktiv.com/sites/default/files/2021-10/Nagios_XI_multiple_vulnerabilities_0.pdf","tags":["Exploit","Third Party Advisory"],"source":"cve@mitre.org"},{"url":"https://assets.nagios.com/downloads/nagiosxi/CHANGES-5.TXT","tags":["Release Notes","Vendor Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://synacktiv.com","tags":["Not Applicable"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://www.synacktiv.com/sites/default/files/2021-10/Nagios_XI_multiple_vulnerabilities_0.pdf","tags":["Exploit","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2021-40344","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."}