CVE-2021-30116
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedKaseya 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.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceKaseya VSA before 9.5.7 contains an unauthenticated credential disclosure vulnerability on the /dl.asp download page. When Windows agents are installed, they create KaseyaD.ini files containing Agent_Guid and AgentPassword credentials, which can be submitted via GET request to dl.asp to obtain a sessionId cookie that bypasses authentication for subsequent attacks.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data< 9.5.0.24< 9.5.7aCVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- 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
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify if Kaseya VSA server is exposedDetermine if your Kaseya VSA web interface (typically ports 80/443) is accessible from untrusted networks or the internet. Review firewall rules and network ACLs restricting access to the VSA management portal.Affected if The Kaseya VSA server is directly accessible from untrusted networks without VPN or IP allowlist restrictions.
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Check Kaseya VSA Server versionLocate the installed Kaseya VSA Server version. This is typically available in the VSA admin console under Help > About, or by examining the installation files or registry on the server itself.Affected if The installed Kaseya VSA Server version is earlier than 9.5.7a.
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Check Kaseya VSA Agent versionLocate the installed Kaseya VSA Agent version on managed endpoints. This can typically be found in Add/Remove Programs, the agent system tray, or via the VSA console under the Agent Details page.Affected if The installed Kaseya VSA Agent version is earlier than 9.5.0.24.
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Test dl.asp page accessibilityAttempt to access the dl.asp page on your VSA server without authentication (e.g., https://<vsa-server>/dl.asp). Observe whether the page loads and whether it returns agent credential information.Affected if The dl.asp page is accessible without authentication and returns Agent_Guid or AgentPassword values.
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Verify credential disclosure vulnerabilitySend a GET request to the dl.asp endpoint and examine the response for embedded credentials (Agent_Guid, AgentPassword) or session cookies that should require authentication.Affected if Unauthenticated requests to dl.asp leak agent credentials or generate valid session cookies.
Your environment is affected if you are running Kaseya VSA Server before version 9.5.7a or Kaseya VSA Agent before version 9.5.0.24, and the dl.asp page is accessible without authentication.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped9.5.0.249.5.7a
Upgrade Kaseya VSA to version 9.5.7 or later to remediate the unauthenticated credential disclosure and authentication bypass vulnerabilities.
Vsa Agent: 9.5.0.24+ | Vsa Server: 9.5.7a+
- Upgrade Vsa Server to version 9.5.7a or later
- Upgrade Vsa Agent to version 9.5.0.24 or later
- After upgrading, verify the /dl.asp page no longer accepts credentials via GET request
- Review agent installations to ensure KaseyaD.ini files are not exposed or can no longer be used for authentication
- Monitor for any unauthorized access attempts using leaked credentials
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation3.0 h
- Implementation6.0 h
- Testing4.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-30116 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-30116 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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