CVE-2021-30116: Kaseya Virtual System/Server Administrator (VSA) Information Disclosure Vulnerability
Reference page built from the source records below, each shown as its source publishes it. Dataset version ref-2ce2efd5c63b, updated 2026-11-02T23:39:54.475Z.
CISA Known Exploited Vulnerabilities
- Name
- Kaseya Virtual System/Server Administrator (VSA) Information Disclosure Vulnerability
- Vendor
- Kaseya
- Product
- Virtual System/Server Administrator (VSA)
- Added to the catalog
- 2021-11-03
- Due date for US federal agencies
- 2021-11-17
- Weaknesses
- CWE-522
- Catalog version
- 2026.10.30
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.
Required action (CISA)
Apply updates per vendor instructions.
Ransomware use: CISA marks this vulnerability as known to be used in ransomware campaigns. CISA does not say which group used it.
Links in CISA's notes
Read on 2026-11-02T23:39:54.475Z under licence cisa-kev-cc0@b0067899 from https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json
NVD analysis
- Status
- Analyzed
- Published
- 2021-07-09T14:15:07.770
- Last modified
- 2026-08-14T05:16:54.497
- Weaknesses
- CWE-522
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.
| Metric | Score | Severity | Vector | Scored by |
|---|---|---|---|---|
| CVSS 3.1 | 10 | CRITICAL | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H | [email protected] (Secondary) |
| CVSS 3.1 | 9.8 | CRITICAL | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H | [email protected] (Primary) |
| CVSS 2.0 | 7.5 | HIGH | AV:N/AC:L/Au:N/C:P/I:P/A:P | [email protected] (Primary) |
References
- https://csirt.divd.nl/2021/07/04/Kaseya-Case-Update-2/ (Third Party Advisory)
- https://csirt.divd.nl/2021/07/07/Kaseya-Limited-Disclosure/ (Third Party Advisory)
- https://helpdesk.kaseya.com/hc/en-gb/articles/4403440684689-Important-Notice-July-2nd-2021 (Vendor Advisory)
- https://www.secpod.com/blog/kaseya-vsa-zero-day-by-revil/ (Exploit, Third Party Advisory)
- https://csirt.divd.nl/2021/07/04/Kaseya-Case-Update-2/ (Third Party Advisory)
- https://csirt.divd.nl/2021/07/07/Kaseya-Limited-Disclosure/ (Third Party Advisory)
- https://helpdesk.kaseya.com/hc/en-gb/articles/4403440684689-Important-Notice-July-2nd-2021 (Vendor Advisory)
- https://www.secpod.com/blog/kaseya-vsa-zero-day-by-revil/ (Exploit, Third Party Advisory)
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-30116 (US Government Resource)
This product uses the NVD API but is not endorsed or certified by the NVD.
Read on 2026-11-02T23:41:51.476Z under licence nvd-api-terms-of-use@ff2a5288 from https://services.nvd.nist.gov/rest/json/cves/2.0?cveId=CVE-2021-30116
CVE record
- Title (CNA)
- Unauthenticated credential leak and business logic flaw in Kaseya VSA <= v9.5.6
- Assigner
- mitre
- State
- PUBLISHED
- Published
- 2021-07-09T00:00:00.000Z
- Updated
- 2026-08-14T03:55:30.740Z
- Problem types
- n/a
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.
References
- https://csirt.divd.nl/2021/07/04/Kaseya-Case-Update-2/
- https://helpdesk.kaseya.com/hc/en-gb/articles/4403440684689-Important-Notice-July-2nd-2021
- https://csirt.divd.nl/2021/07/07/Kaseya-Limited-Disclosure/
- https://www.secpod.com/blog/kaseya-vsa-zero-day-by-revil/
Read on 2026-11-03T01:07:22.032Z under licence cve-terms-of-use@81bfa2f3 from https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2021/30xxx/CVE-2021-30116.json
Defensive techniques (MITRE D3FEND)
D3FEND maps these defensive techniques to the weakness (CWE) that NVD lists for this CVE, through the digital artifacts the weakness affects. D3FEND does not say they stop this vulnerability.
CWE-522: Insufficiently Protected Credentials
- Model: Software Inventory (acts on Software)
- Harden: Trusted Library (acts on Subroutine)
- Model: Asset Vulnerability Enumeration (acts on Software)
- Harden: Software Update (acts on Software)
- Harden: Credential Scrubbing (acts on Subroutine)
- Isolate: Application-based Process Isolation (acts on Subroutine)
- Harden: Variable Initialization (acts on Subroutine)
- Restore: Restore Software (acts on Software)
- Harden: Domain Logic Validation (acts on Subroutine)
D3FEND ontology version 1.6.0.
Read on 2026-11-02T23:57:01.859Z under licence d3fend-terms-of-use@f98cbc7e from https://d3fend.mitre.org/api/weakness/cwe/CWE-522.json
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Sources and licences
CISA
Source: CISA Catalog of Known Exploited Vulnerabilities, version 2026.10.30, CC0 1.0. Use of this data does not imply endorsement by CISA or DHS.
National Vulnerability Database (NIST)
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NVD API Terms of Use (NIST publications in the public domain, 17 U.S.C. 105)
CVE Program, The MITRE Corporation
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MITRE D3FEND
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"The MITRE Corporation (MITRE) hereby grants you a non-exclusive, royalty-free license to use D3FEND for research, development, and commercial purposes. Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy." Terms: https://d3fend.mitre.org/tou/MITRE D3FEND Terms of Use (site + knowledge graph); source repo MIT
Cite this page
Dragons Eye Ransomware Tracker, "CVE-2021-30116: Kaseya Virtual System/Server Administrator (VSA) Information Disclosure Vulnerability",
entity page, dataset version ref-2ce2efd5c63b, updated 2026-11-02T23:39:54.475Z,
https://ransomware-tracker.com/cve/CVE-2021-30116 (accessed 2026-11-03).
Underlying source: CISA Catalog of Known Exploited Vulnerabilities, version 2026.10.30.
Underlying source: National Vulnerability Database (NIST), CVE API 2.0, record last modified 2026-08-14T05:16:54.497.
Underlying source: CVE List (CVE Program, The MITRE Corporation), record updated 2026-08-14T03:55:30.740Z.
Underlying source: MITRE D3FEND, ontology version 1.6.0.
Pages change. The dataset version identifies the data, but no archive of old versions is kept, so this citation cannot be replayed later.