Unauthenticated credential leak and business logic flaw in Kaseya VSA <= v9.5.6

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Summary

CVECVE-2021-30116
StatePUBLISHED
Assignermitre
Source PriorityCVE Program / NVD first with legacy fallback
Published2021-07-09 14:15:07 UTC
Updated2026-08-14 05:16:54 UTC
DescriptionKaseya 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.

Risk And Classification

Primary CVSS: v3.1 9.8 CRITICAL from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS: 0.857350000 probability, percentile 0.997100000 (date 2026-08-21)

CISA KEV: Listed on 2021-11-03; due 2021-11-17; ransomware use Known

Problem Types: CWE-522 | n/a | CWE-522 CWE-522 Insufficiently Protected Credentials

VersionSourceTypeScoreSeverityVector
3.1[email protected]Primary9.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
3.1[email protected]Secondary10CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
3.1CNADECLARED10CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
2.0[email protected]Primary7.5AV:N/AC:L/Au:N/C:P/I:P/A:P

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS v2.0 Breakdown

Access Vector
Network
Access Complexity
Low
Authentication
None
Confidentiality
Partial
Integrity
Partial
Availability
Partial

AV:N/AC:L/Au:N/C:P/I:P/A:P

CISA Known Exploited Vulnerability

VendorKaseya
ProductVirtual System/Server Administrator (VSA)
NameKaseya Virtual System/Server Administrator (VSA) Information Disclosure Vulnerability
Required ActionApply updates per vendor instructions.
Noteshttps://nvd.nist.gov/vuln/detail/CVE-2021-30116

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Kaseya Vsa Agent All All All All
Application Kaseya Vsa Server All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Na N/a affected n/a Not specified

References

ReferenceSourceLinkTags
Kaseya VSA Limited Disclosure | DIVD CSIRT af854a3a-2127-422b-91ae-364da2661108 csirt.divd.nl Third Party Advisory
www.cisa.gov/known-exploited-vulnerabilities-catalog 134c704f-9b21-4f2e-91b3-4a467353bcc0 www.cisa.gov US Government Resource
Kaseya VSA REvil Ransomware Attack 2021 - ransomware attacks 2021 af854a3a-2127-422b-91ae-364da2661108 www.secpod.com Exploit, Third Party Advisory
Kaseya Case Update 2 | DIVD CSIRT af854a3a-2127-422b-91ae-364da2661108 csirt.divd.nl Third Party Advisory
Important Notice July 7th, 2021 – Kaseya af854a3a-2127-422b-91ae-364da2661108 helpdesk.kaseya.com Vendor Advisory
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis
CISA Known Exploited Vulnerabilities catalog CISA www.cisa.gov kev

Vendor Comments And Credit

Discovery Credit

CNA: Discovered by Wietse Boonstra of DIVD (en)

CNA: Additional research by Frank Breedijk of DIVD (en)

Additional Advisory Data

SourceTimeEvent
ADP2021-11-03T00:00:00.000ZCVE-2021-30116 added to CISA KEV

Solutions

CNA: Upgrade to a version after 9.5.6

Legacy QID Mappings

  • 730134 Kaseya VSA Remote Code Execution Vulnerability (Zero Day)

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