CVE-2021-30116

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.

CVSS: 10.0Criticalscored by the publisher (CNA)
Exploited in the wild: Yes, in CISA KEV since 3 Nov 2021CISA deadline for US federal agencies: 17 Nov 2021known use in ransomware campaigns
EPSS: 85.7%chance of exploitation in the next 30 daystop 0.3% of scored CVEsFIRST score of 11 Nov 2026
Fix: Patch availablesee the advisories in the references
Published: 9 Jul 2021analysed here 12 Nov 2026

Do first. Apply updates per vendor instructions. (CISA's required action for this KEV entry)

Summary

Triage

Exploitable: At runtime
Attack vector: network
Weakness: CWE-522 Insufficiently Protected Credentials
Can a WAF block it?: Partly. See why

The summary, impact and action text on this page are written by our AI analysis pipeline, or taken from the NVD description when a CVE was imported from NVD. They are not the vendor's wording: check them against the sources. A longer AI executive summary and technical analysis are generated for signed-in accounts on the Max plan.

Affected products

Products named in our analysis

kaseya:vsa_agent
kaseya:vsa_server

Fix and mitigation

WAF and other mitigations

Can a WAF block it? Partly. The bug can be reached over the network, so generic WAF rules may stop some attacks. Its weakness type is unknown, so we cannot be more precise.

Also consider: patch

Based on the weakness type only; no CVE-specific evidence yet. We check Cloudflare, AWS, Google Cloud Armor and Azure; for Akamai, Imperva, Fastly, F5, ask your vendor.

Remediation steps (AI-written)

Step-by-step remediation is generated for accounts on the Max plan, for CVEs that match a technology in their stack. Add this technology to your stack to see the fix checklist.

Exploitation evidence

CISA KEV catalog: Listed since 3 Nov 2021. Known use in ransomware campaigns.
CISA due date: 17 Nov 2021, the remediation deadline for US federal agencies
CISA required action: Apply updates per vendor instructions.
Public exploit code: Detection templates only, no public exploit found: 1 Nuclei template
CISA SSVC: exploitation active, automatable yes, technical impact totalAssessed by CISA 6 Jul 2021 (SSVC 2.0.3). Exploitation is none, poc (public proof of concept) or active.

Nuclei

Kaseya VSA < 9.5.7 - Credential Disclosure via Windows Agentdetection template, critical

Listed so you can judge urgency, not as a recommendation to run anything. GitHub “proofs of concept” are unvetted: some are fake or carry malware. Exploit-DB marks the entries its staff verified.

Timeline

6 Jul 2021CISA SSVC assessment: exploitation active
9 Jul 2021Published4 days later
3 Nov 2021Added to CISA KEV (exploited in the wild)116 days (about 4 months) later
17 Nov 2021CISA remediation due date (US federal agencies)14 days later
14 Aug 2026CVE record last updated1,731 days (about 5 years) later
12 Nov 2026Analysed by vulneraibility.com90 days (about 3 months) later

CVSS vector

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

Metric	Value	What it means
Attack vector	NetworkReachable over the internet or any routable network.	Reachable over the internet or any routable network.
Attack complexity	LowRepeatable attack, no special conditions.	Repeatable attack, no special conditions.
Privileges required	NoneThe attacker needs no prior access.	The attacker needs no prior access.
User interaction	NoneNo victim action needed.	No victim action needed.
Scope	ChangedImpact crosses a security boundary into other components.	Impact crosses a security boundary into other components.
Confidentiality	HighTotal data disclosure possible.	Total data disclosure possible.
Integrity	HighComplete modification possible.	Complete modification possible.
Availability	HighFull outage possible.	Full outage possible.

Common questions

Is CVE-2021-30116 being exploited?

Yes. CVE-2021-30116 appears in CISA's Known Exploited Vulnerabilities catalog, which means exploitation in the wild has been confirmed and reported. Treat it as active rather than theoretical, and patch it ahead of higher-scoring vulnerabilities that carry no exploitation evidence.

How severe is CVE-2021-30116?

CVE-2021-30116 is rated Critical with a CVSS score of 10.0. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.

Is there a patch for CVE-2021-30116?

Yes. A fix has been recorded for CVE-2021-30116. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.

What does CVE-2021-30116 affect?

CVE-2021-30116 affects kaseya:vsa_agent, kaseya:vsa_server. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.

Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.

References

NVD CVE.org CVE Details Source

5 references in the CVE record, grouped by the tags the record gives them.

Where the data on this page comes from

CVE List (CVE.org): description, affected versions, references; CVE Terms of Use
NVD: CVSS and CPE data
CISA KEV catalog: exploitation, date added, due date
CISA Vulnrichment (ADP): SSVC decision points
FIRST EPSS: exploit probability and percentile
Nuclei templates: detection templates

Summary, impact and triage tags: written by our AI analysis pipeline from the sources above. Check them against the sources.

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