# CVE-2024-36972: af_unix: Update unix_sk(sk)->oob_skb under sk_receive_queue lock.

> A race condition in the Linux kernel's AF_UNIX socket handling can lead to a NULL pointer dereference and system crash.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 10 Jun 2024
- **Updated:** 5 Aug 2026
- **Also known as:** A-342490466, ASB-A-342490466, AZL-48759, AZL-48813, BELL-CVE-2024-36972, DEBIAN-CVE-2024-36972, GHSA-rmff-fqq9-pc3q, UBUNTU-CVE-2024-36972

## What is CVE-2024-36972?

CVE-2024-36972 is a high-severity vulnerability in Linux kernel, published on 10 Jun 2024. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

af_unix: Update unix_sk(sk)->oob_skb under sk_receive_queue lock.

Billy Jheng Bing-Jhong reported a race between __unix_gc() and
queue_oob().

__unix_gc() tries to garbage-collect close()d inflight sockets,
and then if the socket has MSG_OOB in unix_sk(sk)->oob_skb, GC
will drop the reference and set NULL to it locklessly.

However, the peer socket still can send MSG_OOB message and
queue_oob() can update unix_sk(sk)->oob_skb concurrently, leading
NULL pointer dereference. [0]

To fix the issue, let's update unix_sk(sk)->oob_skb under the
sk_receive_queue's lock and take it everywhere we touch oob_skb.

Note that we defer kfree_skb() in manage_oob() to silence lockdep
false-positive (See [1]).

[0]:
BUG: kernel NULL pointer dereference, address: 0000000000000008
 PF: supervisor write access in kernel mode
 PF: error_code(0x0002) - not-present page
PGD 8000000009f5e067 P4D 8000000009f5e067 PUD 9f5d067 PMD 0
Oops: 0002 [#1] PREEMPT SMP PTI
CPU: 3 PID: 50 Comm: kworker/3:1 Not tainted 6.9.0-rc5-00191-gd091e579b864 #110
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014
Workqueue: events delayed_fput
RIP: 0010:skb_dequeue (./include/linux/skbuff.h:2386 ./include/linux/skbuff.h:2402 net/core/skbuff.c:3847)
Code: 39 e3 74 3e 8b 43 10 48 89 ef 83 e8 01 89 43 10 49 8b 44 24 08 49 c7 44 24 08 00 00 00 00 49 8b 14 24 49 c7 04 24 00 00 00 00 <48> 89 42 08 48 89 10 e8 e7 c5 42 00 4c 89 e0 5b 5d 41 5c c3 cc cc
RSP: 0018:ffffc900001bfd48 EFLAGS: 00000002
RAX: 0000000000000000 RBX: ffff8880088f5ae8 RCX: 00000000361289f9
RDX: 0000000000000000 RSI: 0000000000000206 RDI: ffff8880088f5b00
RBP: ffff8880088f5b00 R08: 0000000000080000 R09: 0000000000000001
R10: 0000000000000003 R11: 0000000000000001 R12: ffff8880056b6a00
R13: ffff8880088f5280 R14: 0000000000000001 R15: ffff8880088f5a80
FS:  0000000000000000(0000) GS:ffff88807dd80000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000008 CR3: 0000000006314000 CR4: 00000000007506f0
PKRU: 55555554
Call Trace:
 <TASK>
 unix_release_sock (net/unix/af_unix.c:654)
 unix_release (net/unix/af_unix.c:1050)
 __sock_release (net/socket.c:660)
 sock_close (net/socket.c:1423)
 __fput (fs/file_table.c:423)
 delayed_fput (fs/file_table.c:444 (discriminator 3))
 process_one_work (kernel/workqueue.c:3259)
 worker_thread (kernel/workqueue.c:3329 kernel/workqueue.c:3416)
 kthread (kernel/kthread.c:388)
 ret_from_fork (arch/x86/kernel/process.c:153)
 ret_from_fork_asm (arch/x86/entry/entry_64.S:257)
 </TASK>
Modules linked in:
CR2: 0000000000000008

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2024-36972?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2024-36972?

Apply the vendor's patch.

## Is CVE-2024-36972 being exploited?

There is no known exploitation of CVE-2024-36972 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2024-36972 and fix it if it is affected.

What it is: CVE-2024-36972 is a high-severity vulnerability in Linux kernel, published on 10 Jun 2024. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2024-36972 in the wild and no public exploit code.

Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2024-36972/ (Markdown: https://insights.sbomify.com/CVE-2024-36972/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-36972
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-36972
- OSV: https://osv.dev/vulnerability/CVE-2024-36972

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-36972/
Summaries are generated and may contain mistakes; the official description above is the record.