CVE-2021-30116
CRITICALCISA KEVEPSS 100th pctlDescription
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.
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Exploit Intelligence
Very high risk: more likely to be exploited than 100% of all known CVEs.
Kaseya Virtual System/Server Administrator (VSA) Information Disclosure Vulnerability
Kaseya Virtual System/Server Administrator (VSA) contains an information disclosure vulnerability allowing an attacker to obtain the sessionId that can be used to execute further attacks against the system.
Apply updates per vendor instructions.
Remediation due: 2021-11-17
Associated with ransomware campaigns
References
Related Vulnerabilities
Other CWE-522 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2019-17662 | Critical | 9.8 | 97% | - | - |
| CVE-2020-29583 | Critical | 9.8 | 90% | KEV | - |
| CVE-2024-44000 | Critical | 9.8 | 82% | - | Fix |
| CVE-2018-9160 | Critical | 9.8 | 76% | - | - |
| CVE-2017-9248 | Critical | 9.8 | 75% | KEV | Fix |
| CVE-2014-6039 | High | 7.5 | 69% | - | - |
Common questions
How do I fix CVE-2021-30116?
Published advisories record a fix for 2 affected products. The "How to fix" section on this page lists the fixed version and source advisory for each one, so apply the entry matching what you actually run.
Is CVE-2021-30116 being actively exploited?
Yes. CVE-2021-30116 is listed in the CISA Known Exploited Vulnerabilities catalog, which means exploitation has been observed in the wild. CISA has also linked it to known ransomware campaigns. US federal agencies were required to remediate it by 2021-11-17. Treat it as a priority whatever its CVSS score says.
How severe is CVE-2021-30116?
CVE-2021-30116 has a CVSS v3 base score of 10.0, rated critical. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2021-30116 affect?
Published advisories record a fix for vsa agent (NVD), vsa server (NVD). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-11-10.