{"id":"CVE-2021-30116","url":"https://www.cyber-defence.io/tools/cve/CVE-2021-30116","generatedAt":"2026-10-31T15:06:03.562Z","title":"Kaseya Virtual System/Server Administrator (VSA) Information Disclosure Vulnerability","description":"Kaseya VSA before 9.5.7 allows credential disclosure, as exploited in the wild in July 2021. By default Kaseya VSA on premise offers a download page where the clients for the installation can be downloaded. The default URL for this page is https://x.x.x.x/dl.asp When an attacker download a client for Windows and installs it, the file KaseyaD.ini is generated (C:\\Program Files (x86)\\Kaseya\\XXXXXXXXXX\\KaseyaD.ini) which contains an Agent_Guid and AgentPassword This Agent_Guid and AgentPassword can be used to log in on dl.asp (https://x.x.x.x/dl.asp?un=840997037507813&pw=113cc622839a4077a84837485ced6b93e440bf66d44057713cb2f95e503a06d9) This request authenticates the client and returns a sessionId cookie that can be used in subsequent attacks to bypass authentication. Security issues discovered --- * Unauthenticated download page leaks credentials * Credentials of agent software can be used to obtain a sessionId (cookie) that can be used for services not intended for use by agents * dl.asp accepts credentials via a GET request * Access to KaseyaD.ini gives an attacker access to sufficient information to penetrate the Kaseya installation and its clients. Impact --- Via the page /dl.asp enough information can be obtained to give an attacker a sessionId that can be used to execute further (semi-authenticated) attacks against the system.","published":"2021-07-09T14:15:08.000Z","lastModified":"2026-08-14T05:16:54.000Z","status":"Analyzed","sourceIdentifier":"cve@mitre.org","cvss":{"version":"3.1","score":9.8,"severity":"CRITICAL","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"},"cwe":["CWE-522"],"affected":["kaseya/vsa agent","kaseya/vsa server"],"epss":{"score":0.85735,"percentile":0.99726,"date":"2026-10-30","history":[]},"kev":{"listed":true,"dateAdded":"2021-11-03","dueDate":"2021-11-17","knownRansomwareCampaignUse":"Known","notes":"Apply updates per vendor instructions.\nhttps://nvd.nist.gov/vuln/detail/CVE-2021-30116"},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"urgent","text":"Known to be exploited in the wild (CISA KEV, CISA remediation deadline 17 November 2021). Treat as an emergency change: patch or isolate now, then hunt for prior compromise."},"changes":[],"references":[{"url":"https://csirt.divd.nl/2021/07/04/Kaseya-Case-Update-2/","tags":["Third Party Advisory"],"source":"cve@mitre.org"},{"url":"https://csirt.divd.nl/2021/07/07/Kaseya-Limited-Disclosure/","tags":["Third Party Advisory"],"source":"cve@mitre.org"},{"url":"https://helpdesk.kaseya.com/hc/en-gb/articles/4403440684689-Important-Notice-July-2nd-2021","tags":["Vendor Advisory"],"source":"cve@mitre.org"},{"url":"https://www.secpod.com/blog/kaseya-vsa-zero-day-by-revil/","tags":["Exploit","Third Party Advisory"],"source":"cve@mitre.org"},{"url":"https://csirt.divd.nl/2021/07/04/Kaseya-Case-Update-2/","tags":["Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://csirt.divd.nl/2021/07/07/Kaseya-Limited-Disclosure/","tags":["Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://helpdesk.kaseya.com/hc/en-gb/articles/4403440684689-Important-Notice-July-2nd-2021","tags":["Vendor Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://www.secpod.com/blog/kaseya-vsa-zero-day-by-revil/","tags":["Exploit","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-30116","tags":["US Government Resource"],"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2021-30116","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."}