CVE-2021-30116
9.8, critical Known exploited Used in ransomwareKaseya Virtual System/Server Administrator (VSA) Information Disclosure Vulnerability
- CVSS
- 9.8, critical critical CVSS v3.1
- EPSS, next 30 days
- 86% higher than 99.7% of scored CVEs
- Exploitation
- Confirmed in the wild
- Published
- 9 Jul 20215 years ago
Known exploited
CISA added this to the Known Exploited Vulnerabilities Catalog on 3 Nov 2021 and links it to ransomware activity. US federal agencies had to remediate by 17 Nov 2021, a deadline that has passed.
Required action. Apply updates per vendor instructions.
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.
Details
- Vendor
- Kaseya
- Product
- Vsa Agent
- Weakness
- CWE-522 (opens in a new tab)
- Status
- Analyzed
- Updated
- 14 Aug 2026
- Assigner
- cve@mitre.org
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
References 5
Advisories 3
The kind is read from NVD's tags where present and from the shape of the URL otherwise, so treat it as a hint.
Other Kaseya CVEs
Every Kaseya CVE we holdSame vendor in what we hold, not a known link between the flaws.
- CVE-2017-18362 Kaseya VSA SQL Injection Vulnerability KEV EPSS 87% 9.8, critical
- CVE-2018-20753 Kaseya VSA Remote Code Execution Vulnerability KEV EPSS 30% 9.8, critical
Beyond this page
Is CVE-2021-30116 in your network?
This page tells you how dangerous CVE-2021-30116 is out there. Whether it sits on one of your devices, only a scan of your own network can tell. That is what our systems do, every day, for the companies we protect.
CVE-2021-30116 is in the CISA catalogue of exploited vulnerabilities: attackers are already exploiting it.
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EXYS7600 OCELOT
Find it before attackers do
Ocelot scans your network on a schedule and reports every vulnerability it finds by its CVE identifier, with its CVSS score and how many of your hosts are affected. A finding like CVE-2021-30116 comes with the devices to patch.
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EXYS7950 KONDRA
Detect it if it's exploited
Until the patch is applied, Kondra monitors your network, events and endpoints in real time. It keeps an inventory of the software installed on every endpoint, and its anomaly detection rules flag what an attacker does once inside.
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Assembled from the NVD 2.0 API, the CISA Known Exploited Vulnerabilities Catalog and FIRST EPSS. Scores are as of our last collection on 17 Oct 2026, not the live upstream state.