{"id":"CVE-2021-30116","published":"2021-07-09T14:15:07Z","modified":"2026-08-14T05:16:54Z","title":"Kaseya Virtual System/Server Administrator (VSA) Information Disclosure Vulnerability","vendor":"Kaseya","product":"Virtual System/Server Administrator (VSA)","tier":"core","eol":null,"description":{"text":"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.","provenance":"source","from":"NVD"},"summary":{"text":"Kaseya Virtual System/Server Administrator (VSA) before 9.5.7 contains an information disclosure flaw in its default, unauthenticated client download page (/dl.asp), which exposes agent credentials. An attacker needs only network access to the VSA server and no authentication or user interaction: they can download and install the Windows client, read the resulting KaseyaD.ini file to obtain the agent GUID and password, and use those credentials at /dl.asp to obtain a session cookie for further attacks against the system.","provenance":"ai","model":"claude-haiku-5-5","generatedAt":"2026-10-23T06:55:22Z"},"cvss":{"score":9.8,"severity":"CRITICAL","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","provenance":"source","from":"NVD"},"epss":{"score":0.85735,"percentile":0.99726,"date":"2026-10-29","provenance":"source"},"kev":{"dateAdded":"2021-11-03","dueDate":"2021-11-17","ransomware":true,"requiredAction":"Apply updates per vendor instructions.","notes":"https://nvd.nist.gov/vuln/detail/CVE-2021-30116","provenance":"source"},"vulncheckKev":{"dateAdded":"2021-07-02","exploitedFirstSeen":"2021-07-02","ransomware":true,"evidence":[{"url":"https://blog.talosintelligence.com/2021/07/revil-ransomware-actors-attack-kaseya.html","date":"2021-07-02"},{"url":"https://www.huntress.com/blog/rapid-response-kaseya-vsa-mass-msp-ransomware-incident","date":"2021-07-03"},{"url":"https://blog.truesec.com/2021/07/04/kaseya-supply-chain-attack-targeting-msps-to-deliver-revil-ransomware/","date":"2021-07-04"},{"url":"https://unit42.paloaltonetworks.com/revil-threat-actors/","date":"2021-07-06"},{"url":"https://www.tenable.com/blog/cve-2021-30116-multiple-zero-day-vulnerabilities-in-kaseya-vsa-exploited-to-distribute-ransomware","date":"2021-07-06"},{"url":"https://www.crowdstrike.com/blog/how-crowdstrike-stops-revil-ransomware-from-kaseya-attack/","date":"2021-07-07"},{"url":"https://www.cve.org/CVERecord?id=CVE-2021-30116","date":"2021-07-09"},{"url":"https://threatpost.com/kaseya-patches-zero-days-revil-attacks/167670/","date":"2021-07-12"},{"url":"https://www.akamai.com/blog/security/kaseya-supply-chain-ransomware-attack","date":"2021-07-15"},{"url":"https://www.hhs.gov/sites/default/files/revil-update-tlpwhite.pdf","date":"2021-08-19"}],"evidenceTotal":19,"provenance":"source"},"exploited":true,"otx":{"pulseCount":50,"pulses":[{"name":"Actively_Exploited_Kev | Oct 29, 2026","url":"https://otx.alienvault.com/pulse/6ae20c1db17e7057ae7d9ad1","created":"2026-10-28"},{"name":"Actively_Exploited_Kev | Oct 28, 2026","url":"https://otx.alienvault.com/pulse/6ae0ba7e0e2a97ff7b218819","created":"2026-10-27"},{"name":"Actively_Exploited_Kev | Oct 27, 2026","url":"https://otx.alienvault.com/pulse/6adf68b85c3e852f3c111d18","created":"2026-10-26"},{"name":"Actively_Exploited_Kev | Oct 24, 2026","url":"https://otx.alienvault.com/pulse/6adb740e397c3ad4799aa4cd","created":"2026-10-23"},{"name":"Actively_Exploited_Kev | Oct 23, 2026","url":"https://otx.alienvault.com/pulse/6ada236fcfba2dfa730ea482","created":"2026-10-22"},{"name":"Actively_Exploited_Kev | Oct 22, 2026","url":"https://otx.alienvault.com/pulse/6ad8d33a077cbb5cab524d80","created":"2026-10-21"},{"name":"Actively_Exploited_Kev | Oct 21, 2026","url":"https://otx.alienvault.com/pulse/6ad78130c4d1ac2be83a8b6d","created":"2026-10-20"},{"name":"Actively_Exploited_Kev | Oct 20, 2026","url":"https://otx.alienvault.com/pulse/6ad62f63c24a405a3423cc13","created":"2026-10-19"},{"name":"Actively_Exploited_Kev | Oct 19, 2026","url":"https://otx.alienvault.com/pulse/6ad4dda174e5797d0bd238b7","created":"2026-10-18"},{"name":"Actively_Exploited_Kev | Oct 18, 2026","url":"https://otx.alienvault.com/pulse/6ad38c22e1848f8189d1c121","created":"2026-10-17"}],"provenance":"machine"},"cwes":[{"id":"CWE-522","name":"Insufficiently Protected Credentials"}],"references":[{"url":"https://csirt.divd.nl/2021/07/04/Kaseya-Case-Update-2/","tags":["Third Party Advisory"]},{"url":"https://csirt.divd.nl/2021/07/07/Kaseya-Limited-Disclosure/","tags":["Third Party Advisory"]},{"url":"https://helpdesk.kaseya.com/hc/en-gb/articles/4403440684689-Important-Notice-July-2nd-2021","tags":["Vendor Advisory"]},{"url":"https://www.secpod.com/blog/kaseya-vsa-zero-day-by-revil/","tags":["Exploit","Third Party Advisory"]},{"url":"https://csirt.divd.nl/2021/07/04/Kaseya-Case-Update-2/","tags":["Third Party Advisory"]},{"url":"https://csirt.divd.nl/2021/07/07/Kaseya-Limited-Disclosure/","tags":["Third Party Advisory"]},{"url":"https://helpdesk.kaseya.com/hc/en-gb/articles/4403440684689-Important-Notice-July-2nd-2021","tags":["Vendor Advisory"]},{"url":"https://www.secpod.com/blog/kaseya-vsa-zero-day-by-revil/","tags":["Exploit","Third Party Advisory"]},{"url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-30116","tags":["US Government Resource"]}],"techniques":[{"id":"T1190","name":"Exploit Public-Facing Application","tactics":["initial-access"],"provenance":"ai","basis":"ai-mapping","bases":["ai-mapping"],"basisDetail":"claude-haiku-5-5: unauthenticated public-facing web page exposes credentials","mappingType":"exploitation_technique","evidence":[{"from":"description","quote":"The default URL for this page is https://x.x.x.x/dl.asp","start":207,"end":262}],"model":"claude-haiku-5-5","confidence":"medium","confidenceNote":"AI-mapped from the description (quote-validated, not expert-reviewed)"},{"id":"T1552","name":"Unsecured Credentials","tactics":["credential-access"],"provenance":"ai","basis":"ai-mapping","bases":["ai-mapping"],"basisDetail":"claude-haiku-5-5: agent credentials stored in readable config file","mappingType":"primary_impact","evidence":[{"from":"description","quote":"KaseyaD.ini is generated (C:\\Program Files (x86)\\Kaseya\\XXXXXXXXXX\\KaseyaD.ini) which contains an Agent_Guid and AgentPassword","start":336,"end":462}],"model":"claude-haiku-5-5","confidence":"medium","confidenceNote":"AI-mapped from the description (quote-validated, not expert-reviewed)"}],"reports":[{"id":"SRC-859cbc7ab52c526327fa","title":"The cyber threat from supply chains - Canadian Centre for Cyber Security","publisher":"cyber.gc.ca","url":"https://www.cyber.gc.ca/en/guidance/cyber-threat-supply-chains","date":null,"mentions":[{"quote":"The 2021 Kaseya VSA compromise by REvil used several zero-day vulnerabilities, including CVE-2021-30116Footnote 4 and CVE-2021-30120,Footnote 5 which allowed them to bypass authentication requirements to access VSA servers en route to deploying ransomware in up to 1500 downstream client networks.Footnote 6","start":11029,"end":11336},{"quote":"“CVE-2021-30116 Detail.”","start":35046,"end":35070}]}],"affected":[],"advisories":[],"euvd":{"id":"EUVD-2021-17056","url":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2021-17056","exploited":true,"exploitedSince":"2021-11-03","provenance":"source"},"exploits":[],"exploitSources":{"nuclei":[{"id":"CVE-2021-30116","name":"Kaseya VSA < 9.5.7 - Credential Disclosure via Windows Agent","severity":"critical","path":"http/cves/2021/CVE-2021-30116.yaml","url":"https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2021/CVE-2021-30116.yaml"}],"provenance":"source"},"exploitRefs":["https://www.secpod.com/blog/kaseya-vsa-zero-day-by-revil/"],"flow":[{"stage":"exploitation","techniques":["T1190"],"provenance":"ai"},{"stage":"primary","techniques":["T1552"],"provenance":"ai"}],"timeline":[{"date":"2021-07-02","kind":"exploited-reported","label":"Exploitation first reported (VulnCheck KEV evidence)","url":"https://blog.talosintelligence.com/2021/07/revil-ransomware-actors-attack-kaseya.html","provenance":"source"},{"date":"2021-07-09","kind":"published","label":"Published (NVD)","url":"https://nvd.nist.gov/vuln/detail/CVE-2021-30116","provenance":"source"},{"date":"2021-11-03","kind":"kev","label":"Added to CISA KEV (known ransomware use)","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","provenance":"source"},{"date":"2021-11-03","kind":"euvd-exploited","label":"ENISA EUVD: exploited","url":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2021-17056","provenance":"source"}],"speed":{"daysToPublicExploit":null,"firstExploitFrom":null,"daysToKev":117},"priority":{"score":83.7,"factors":[{"name":"In a KEV catalog","points":35.0,"detail":"listed in CISA KEV and VulnCheck KEV"},{"name":"Recent KEV listing","points":0.0,"detail":"added 1945 days ago"},{"name":"Known ransomware use","points":10.0,"detail":"CISA KEV and VulnCheck KEV: Known"},{"name":"EPSS percentile","points":19.95,"detail":"percentile 0.9973"},{"name":"Named in threat reports","points":3.87,"detail":"1 report"},{"name":"Public exploit code","points":5.0,"detail":"1 NVD reference tagged Exploit; 1 nuclei template"},{"name":"Mentioned in OTX pulses","points":3.0,"detail":"50 pulses"},{"name":"CVSS severity","points":6.86,"detail":"base score 9.8"},{"name":"End-of-life product","points":0.0,"detail":"supported or unknown"}]}}