# CVE-2024-42321: net: flow_dissector: use DEBUG_NET_WARN_ON_ONCE

> A kernel warning in the flow dissector can be triggered by network traffic, potentially causing system instability or denial of service.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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:** 17 Aug 2024
- **Updated:** 11 May 2026
- **Also known as:** AZL-68357, BELL-CVE-2024-42321, DEBIAN-CVE-2024-42321, GHSA-h7cj-mmqx-xq6g, ROOT-OS-DEBIAN-11-CVE-2024-42321, ROOT-OS-UBUNTU-2204-CVE-2024-42321, UBUNTU-CVE-2024-42321

## What is CVE-2024-42321?

CVE-2024-42321 is a medium-severity denial of service vulnerability in Linux kernel, published on 17 Aug 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:

net: flow_dissector: use DEBUG_NET_WARN_ON_ONCE

The following splat is easy to reproduce upstream as well as in -stable
kernels. Florian Westphal provided the following commit:

  d1dab4f71d37 ("net: add and use __skb_get_hash_symmetric_net")

but this complementary fix has been also suggested by Willem de Bruijn
and it can be easily backported to -stable kernel which consists in
using DEBUG_NET_WARN_ON_ONCE instead to silence the following splat
given __skb_get_hash() is used by the nftables tracing infrastructure to
to identify packets in traces.

[69133.561393] ------------[ cut here ]------------
[69133.561404] WARNING: CPU: 0 PID: 43576 at net/core/flow_dissector.c:1104 __skb_flow_dissect+0x134f/
[...]
[69133.561944] CPU: 0 PID: 43576 Comm: socat Not tainted 6.10.0-rc7+ #379
[69133.561959] RIP: 0010:__skb_flow_dissect+0x134f/0x2ad0
[69133.561970] Code: 83 f9 04 0f 84 b3 00 00 00 45 85 c9 0f 84 aa 00 00 00 41 83 f9 02 0f 84 81 fc ff
ff 44 0f b7 b4 24 80 00 00 00 e9 8b f9 ff ff <0f> 0b e9 20 f3 ff ff 41 f6 c6 20 0f 84 e4 ef ff ff 48 8d 7b 12 e8
[69133.561979] RSP: 0018:ffffc90000006fc0 EFLAGS: 00010246
[69133.561988] RAX: 0000000000000000 RBX: ffffffff82f33e20 RCX: ffffffff81ab7e19
[69133.561994] RDX: dffffc0000000000 RSI: ffffc90000007388 RDI: ffff888103a1b418
[69133.562001] RBP: ffffc90000007310 R08: 0000000000000000 R09: 0000000000000000
[69133.562007] R10: ffffc90000007388 R11: ffffffff810cface R12: ffff888103a1b400
[69133.562013] R13: 0000000000000000 R14: ffffffff82f33e2a R15: ffffffff82f33e28
[69133.562020] FS:  00007f40f7131740(0000) GS:ffff888390800000(0000) knlGS:0000000000000000
[69133.562027] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[69133.562033] CR2: 00007f40f7346ee0 CR3: 000000015d200001 CR4: 00000000001706f0
[69133.562040] Call Trace:
[69133.562044]  <IRQ>
[69133.562049]  ? __warn+0x9f/0x1a0
[ 1211.841384]  ? __skb_flow_dissect+0x107e/0x2860
[...]
[ 1211.841496]  ? bpf_flow_dissect+0x160/0x160
[ 1211.841753]  __skb_get_hash+0x97/0x280
[ 1211.841765]  ? __skb_get_hash_symmetric+0x230/0x230
[ 1211.841776]  ? mod_find+0xbf/0xe0
[ 1211.841786]  ? get_stack_info_noinstr+0x12/0xe0
[ 1211.841798]  ? bpf_ksym_find+0x56/0xe0
[ 1211.841807]  ? __rcu_read_unlock+0x2a/0x70
[ 1211.841819]  nft_trace_init+0x1b9/0x1c0 [nf_tables]
[ 1211.841895]  ? nft_trace_notify+0x830/0x830 [nf_tables]
[ 1211.841964]  ? get_stack_info+0x2b/0x80
[ 1211.841975]  ? nft_do_chain_arp+0x80/0x80 [nf_tables]
[ 1211.842044]  nft_do_chain+0x79c/0x850 [nf_tables]

## Which versions are affected by CVE-2024-42321?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2024-42321?

Apply the vendor's patch.

## Is CVE-2024-42321 being exploited?

There is no known exploitation of CVE-2024-42321 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-2024-42321 and fix it if it is affected.

What it is: CVE-2024-42321 is a medium-severity denial of service vulnerability in Linux kernel, published on 17 Aug 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-2024-42321 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-2024-42321/ (Markdown: https://insights.sbomify.com/CVE-2024-42321/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-42321
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-42321
- OSV: https://osv.dev/vulnerability/CVE-2024-42321

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-42321/
Summaries are generated and may contain mistakes; the official description above is the record.