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.
CVE-2021-30116
Score elevated to 9.8 because this CVE is listed on the CISA Known Exploited Vulnerabilities catalog (added 2021-11-03), indicating real-world exploitation has been confirmed by US federal agencies. NVD baseline CVSS 9.8 retained for reference. Confidence: HIGH.
- Actively exploited in the wild (CISA-KEV)
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 9.8
- EG Score
- 9.8(high)
- EG Risk
- 99(Act)EG Risk 99/100SSVC: Act
EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).
How it’s computedSeverity98% × 45%Exploitation100% × 40%Automatability100% × 15%Action: Fix now — active exploitation, automatable, high impact. - EPSS PROB
- 86%
- EPSS %ILE
- 100%
- KEV
- ⚠ Exploited
Published
July 9, 2021
Last Modified
August 14, 2026
Advisory Details (4)
Auto-updated Sep 18, 2026Known Exploited Vulnerabilities Catalog | CISA
Known Exploited Vulnerabilities Catalog | CISA. Listed in CISA Known Exploited Vulnerabilities catalog.
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-30116Kaseya’s Virtual System/Server Administrator (VSA) Zero-Day Under Acti | SecPod
https://www.secpod.com/blog/kaseya-vsa-zero-day-by-revil/Kaseya VSA Limited Disclosure | DIVD CSIRT
https://csirt.divd.nl/2021/07/07/Kaseya-Limited-Disclosure/Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 56× in last 7d / 237× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
Showing the most recent 100 of 854 total refreshes for this CVE.
- 2026-09-20 00:55 UTCGHSA enrichment
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- 2026-09-17 04:30 UTCGHSA enrichment
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- 2026-09-14 19:24 UTCCISA KEV update
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- 2026-09-11 19:11 UTCGHSA enrichment
- 2026-09-11 18:49 UTCCISA KEV update
- 2026-09-11 15:23 UTCGHSA enrichment
- 2026-09-11 11:35 UTCGHSA enrichment
- 2026-09-11 07:44 UTCGHSA enrichment
- 2026-09-11 03:56 UTCGHSA enrichment
- 2026-09-11 00:08 UTCGHSA enrichment
- 2026-09-10 20:19 UTCGHSA enrichment
- 2026-09-10 19:28 UTCCISA KEV update
- 2026-09-10 16:31 UTCGHSA enrichment
- 2026-09-10 12:43 UTCEG score recompute
- 2026-09-10 12:43 UTCGHSA enrichment
- 2026-09-10 08:54 UTCGHSA enrichment
- 2026-09-10 05:05 UTCGHSA enrichment
- 2026-09-10 01:17 UTCGHSA enrichment
- 2026-09-09 21:29 UTCGHSA enrichment
- 2026-09-09 19:08 UTCCISA KEV update
- 2026-09-09 17:41 UTCGHSA enrichment
- 2026-09-09 13:53 UTCGHSA enrichment
- 2026-09-09 10:05 UTCGHSA enrichment
- 2026-09-09 06:17 UTCGHSA enrichment
- 2026-09-09 02:30 UTCGHSA enrichment
- 2026-09-08 22:40 UTCGHSA enrichment
- 2026-09-08 18:54 UTCCISA KEV update
- 2026-09-08 18:50 UTCGHSA enrichment
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- 2026-09-08 11:13 UTCGHSA enrichment
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- 2026-09-08 03:35 UTCGHSA enrichment
- 2026-09-07 23:46 UTCGHSA enrichment
- 2026-09-07 19:58 UTCGHSA enrichment
- 2026-09-07 16:10 UTCEG score recompute
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- 2026-09-07 15:58 UTCEPSS rescore
- 2026-09-07 12:21 UTCGHSA enrichment
- 2026-09-07 08:33 UTCGHSA enrichment
Publicly available exploits
(1 reference)Working exploit code is in the public domain. Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.
- Nucleihttp/cves/2021/CVE-2021-30116.yamlFirst seen Jan 1, 2021
Kaseya VSA < 9.5.7 - Credential Disclosure via Windows Agent
Open source ↗
Frequently asked(6)
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Dependency Blast Radius
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