# CVE-2023-53333: netfilter: conntrack: dccp: copy entire header to stack buffer, not just basic one

> A stack-out-of-bounds read in the Linux kernel's DCCP conntrack module allows attackers to cause a denial of service or leak sensitive memory information.

- **Severity:** High 8.2 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 16 Sep 2025
- **Updated:** 5 Aug 2026
- **Also known as:** BELL-CVE-2023-53333, DEBIAN-CVE-2023-53333, GHSA-r2m9-j67m-7grm, UBUNTU-CVE-2023-53333

## What is CVE-2023-53333?

CVE-2023-53333 is a high-severity memory corruption vulnerability in Linux kernel, published on 16 Sep 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

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

netfilter: conntrack: dccp: copy entire header to stack buffer, not just basic one

Eric Dumazet says:
  nf_conntrack_dccp_packet() has an unique:

  dh = skb_header_pointer(skb, dataoff, sizeof(_dh), &_dh);

  And nothing more is 'pulled' from the packet, depending on the content.
  dh->dccph_doff, and/or dh->dccph_x ...)
  So dccp_ack_seq() is happily reading stuff past the _dh buffer.

BUG: KASAN: stack-out-of-bounds in nf_conntrack_dccp_packet+0x1134/0x11c0
Read of size 4 at addr ffff000128f66e0c by task syz-executor.2/29371
[..]

Fix this by increasing the stack buffer to also include room for
the extra sequence numbers and all the known dccp packet type headers,
then pull again after the initial validation of the basic header.

While at it, mark packets invalid that lack 48bit sequence bit but
where RFC says the type MUST use them.

Compile tested only.

v2: first skb_header_pointer() now needs to adjust the size to
    only pull the generic header. (Eric)

Heads-up: I intend to remove dccp conntrack support later this year.

Weakness: CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2023-53333?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2023-53333?

Apply the vendor's patch.

## Is CVE-2023-53333 being exploited?

There is no known exploitation of CVE-2023-53333 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-2023-53333 and fix it if it is affected.

What it is: CVE-2023-53333 is a high-severity memory corruption vulnerability in Linux kernel, published on 16 Sep 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2023-53333 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-2023-53333/ (Markdown: https://insights.sbomify.com/CVE-2023-53333/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-53333
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-53333
- OSV: https://osv.dev/vulnerability/CVE-2023-53333

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-53333/
Summaries are generated and may contain mistakes; the official description above is the record.