# CVE-2024-56642: tipc: Fix use-after-free of kernel socket in cleanup_bearer().

> A use-after-free vulnerability in the Linux kernel's TIPC module allows attackers to cause a denial of service or potentially execute code.

- **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:** 27 Dec 2024
- **Updated:** 5 Aug 2026
- **Also known as:** AZL-55163, AZL-55214, BELL-CVE-2024-56642, DEBIAN-CVE-2024-56642, GHSA-wp52-h62r-qwj4, UBUNTU-CVE-2024-56642

## What is CVE-2024-56642?

CVE-2024-56642 is a high-severity use after free vulnerability in Linux kernel, published on 27 Dec 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:

tipc: Fix use-after-free of kernel socket in cleanup_bearer().

syzkaller reported a use-after-free of UDP kernel socket
in cleanup_bearer() without repro. [0][1]

When bearer_disable() calls tipc_udp_disable(), cleanup
of the UDP kernel socket is deferred by work calling
cleanup_bearer().

tipc_exit_net() waits for such works to finish by checking
tipc_net(net)->wq_count.  However, the work decrements the
count too early before releasing the kernel socket,
unblocking cleanup_net() and resulting in use-after-free.

Let's move the decrement after releasing the socket in
cleanup_bearer().

[0]:
ref_tracker: net notrefcnt@000000009b3d1faf has 1/1 users at
     sk_alloc+0x438/0x608
     inet_create+0x4c8/0xcb0
     __sock_create+0x350/0x6b8
     sock_create_kern+0x58/0x78
     udp_sock_create4+0x68/0x398
     udp_sock_create+0x88/0xc8
     tipc_udp_enable+0x5e8/0x848
     __tipc_nl_bearer_enable+0x84c/0xed8
     tipc_nl_bearer_enable+0x38/0x60
     genl_family_rcv_msg_doit+0x170/0x248
     genl_rcv_msg+0x400/0x5b0
     netlink_rcv_skb+0x1dc/0x398
     genl_rcv+0x44/0x68
     netlink_unicast+0x678/0x8b0
     netlink_sendmsg+0x5e4/0x898
     ____sys_sendmsg+0x500/0x830

[1]:
BUG: KMSAN: use-after-free in udp_hashslot include/net/udp.h:85 [inline]
BUG: KMSAN: use-after-free in udp_lib_unhash+0x3b8/0x930 net/ipv4/udp.c:1979
 udp_hashslot include/net/udp.h:85 [inline]
 udp_lib_unhash+0x3b8/0x930 net/ipv4/udp.c:1979
 sk_common_release+0xaf/0x3f0 net/core/sock.c:3820
 inet_release+0x1e0/0x260 net/ipv4/af_inet.c:437
 inet6_release+0x6f/0xd0 net/ipv6/af_inet6.c:489
 __sock_release net/socket.c:658 [inline]
 sock_release+0xa0/0x210 net/socket.c:686
 cleanup_bearer+0x42d/0x4c0 net/tipc/udp_media.c:819
 process_one_work kernel/workqueue.c:3229 [inline]
 process_scheduled_works+0xcaf/0x1c90 kernel/workqueue.c:3310
 worker_thread+0xf6c/0x1510 kernel/workqueue.c:3391
 kthread+0x531/0x6b0 kernel/kthread.c:389
 ret_from_fork+0x60/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:244

Uninit was created at:
 slab_free_hook mm/slub.c:2269 [inline]
 slab_free mm/slub.c:4580 [inline]
 kmem_cache_free+0x207/0xc40 mm/slub.c:4682
 net_free net/core/net_namespace.c:454 [inline]
 cleanup_net+0x16f2/0x19d0 net/core/net_namespace.c:647
 process_one_work kernel/workqueue.c:3229 [inline]
 process_scheduled_works+0xcaf/0x1c90 kernel/workqueue.c:3310
 worker_thread+0xf6c/0x1510 kernel/workqueue.c:3391
 kthread+0x531/0x6b0 kernel/kthread.c:389
 ret_from_fork+0x60/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:244

CPU: 0 UID: 0 PID: 54 Comm: kworker/0:2 Not tainted 6.12.0-rc1-00131-gf66ebf37d69c #7 91723d6f74857f70725e1583cba3cf4adc716cfa
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
Workqueue: events cleanup_bearer

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2024-56642?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2024-56642?

Apply the vendor's patch.

## Is CVE-2024-56642 being exploited?

There is no known exploitation of CVE-2024-56642 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-2024-56642 and fix it if it is affected.

What it is: CVE-2024-56642 is a high-severity use after free vulnerability in Linux kernel, published on 27 Dec 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-2024-56642 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-2024-56642/ (Markdown: https://insights.sbomify.com/CVE-2024-56642/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-56642
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-56642
- OSV: https://osv.dev/vulnerability/CVE-2024-56642

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-56642/
Summaries are generated and may contain mistakes; the official description above is the record.