Threats / Kaseya / CVE-2018-20753
CVE-2018-20753
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-09-19
Kaseya Virtual System/Server Administrator (VSA) vulnerability
Kaseya VSA allows unprivileged remote attackers to execute arbitrary PowerShell commands on all managed devices, enabling widespread compromise of customer infrastructure.
Verdict
Today item, not a backlog item.
A remote code execution vulnerability in Kaseya VSA permits unauthenticated or low-privilege attackers to deploy malicious PowerShell payloads across managed endpoints without authentication, facilitating ransomware distribution and lateral movement at scale.
CISA KEV Yes · 2022-04-134Ransomware use Flagged4EPSS 0.29336 (verify live)5CVSS 9.8 (CISA)3CISA SSVC Exploitation: active · Automatable: yes · Impact: total3
01
Is it exploitable?
— the evidence, ranked above the scoreReported exploitation
2 independent public reports of in-the-wild exploitation are cataloged.Distinct reporting sources (vendor, incident response, government); open them for the underlying claims.
Exploited in the wild
Listed in the CISA Known Exploited Vulnerabilities catalog (added 2022-04-13), flagged for known ransomware use.
Probability (EPSS)
EPSS 0.29336 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
CVSS 9.8 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H) · Affected: Kaseya, Virtual System/Server Administrator (VSA). Confirm exact fixed builds in the vendor advisory.CVSS — CISA-assigned via the ADP container (CVE.org), version 3.1; the CNA left no metrics, so CISA's own score is used ahead of NVD.
CISA SSVC (triage disposition)
Exploitation: active · Automatable: yes · Technical Impact: totalCISA's own stakeholder-specific triage inputs, published in the CVE record (CISA Coordinator role). NOTE: this is CISA's three decision points; the final Act/Attend/Track decision also requires a Mission & Well-being input not published here, so no overall decision is asserted.
Currency of the record
CISA added this to its KEV catalog 1163 days after the CVE record was published.KEV lag = CISA-KEV dateAdded − CVE.org datePublished; a floor on how long the known-exploited flaw sat in the public record before the federal catalog listed it. Severity/weakness here is CNA- or CISA-assigned (current at disclosure), independent of NVD's analysis backlog.
02
Who’s exploiting it?
— attribution turns risk into urgencyAttribution not established
No confirmed (advisory-backed) threat-actor attribution is established for this record. Absence of a named actor is not absence of compromise — see Coverage & confidence.
03
Why it matters
— the attack path, told twice: adversary, then board1
Front door — unauthenticated access narrative 1
Attacker
I identify Kaseya VSA as an internet-exposed remote management platform used by managed service providers.
Business
The organization relies on VSA to manage thousands of customer endpoints across multiple industries.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I send a crafted request to VSA that bypasses authentication controls and executes arbitrary PowerShell code.
Business
The vulnerability allows a single attacker interaction to compromise all connected managed devices simultaneously.
3
Lateral reach — past segmentation narrative 3
Attacker
I deploy ransomware payloads via PowerShell execution across the entire managed device fleet.
Business
Customers experience coordinated encryption of critical systems, with ransom demands affecting business continuity across multiple organizations.
4
Data at risk — exfiltration narrative 4
Attacker
I maintain persistence and exfiltrate sensitive data from compromised endpoints before encryption.
Business
The organization faces regulatory penalties, customer liability claims, and reputational damage from the supply-chain attack vector.
04
What to do
— defensible action- Remediate per the vendor advisory — confirm the fixed build for your version and verify exposure.1
Say it to the boardA vulnerability with this evidence profile is a defensible budget line, not a backlog ticket — fund the change against the proof above.
05
Coverage & confidence
— what we know, and what we don’tEstablished (cited)
Coverage gaps — stated, not hidden
Disclosure & credit2
Catalogued by mitreCNA
Credited with finding itNo finder is named in the public CVE record or the scanned vendor advisory — attribution scoped to the sources checked.
Found an error? Propose a correction.
A correction is a cited counter-claim — it must cite a source,
gets reviewed by a second human, and is never auto-applied. See the
correction convention and our identity
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