# CVE-2023-53669: tcp: fix skb_copy_ubufs() vs BIG TCP

> A flaw in the Linux kernel TCP stack causes crashes when handling large packets with zerocopy, leading to denial of service.

- **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:** 7 Oct 2025
- **Updated:** 15 Oct 2026
- **Also known as:** BELL-CVE-2023-53669, DEBIAN-CVE-2023-53669, GHSA-3p8v-593f-mgx8, UBUNTU-CVE-2023-53669

## What is CVE-2023-53669?

CVE-2023-53669 is a high-severity denial of service vulnerability in Linux kernel, published on 7 Oct 2025. 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:

tcp: fix skb_copy_ubufs() vs BIG TCP

David Ahern reported crashes in skb_copy_ubufs() caused by TCP tx zerocopy
using hugepages, and skb length bigger than ~68 KB.

skb_copy_ubufs() assumed it could copy all payload using up to
MAX_SKB_FRAGS order-0 pages.

This assumption broke when BIG TCP was able to put up to 512 KB per skb.

We did not hit this bug at Google because we use CONFIG_MAX_SKB_FRAGS=45
and limit gso_max_size to 180000.

A solution is to use higher order pages if needed.

v2: add missing __GFP_COMP, or we leak memory.

Weakness: CWE-401 (Missing Release of Memory after Effective Lifetime)

## Which versions are affected by CVE-2023-53669?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2023-53669?

Apply the vendor's patch.

## Is CVE-2023-53669 being exploited?

There is no known exploitation of CVE-2023-53669 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-2023-53669 and fix it if it is affected.

What it is: CVE-2023-53669 is a high-severity denial of service vulnerability in Linux kernel, published on 7 Oct 2025. 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-2023-53669 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-2023-53669/ (Markdown: https://insights.sbomify.com/CVE-2023-53669/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-53669
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-53669
- OSV: https://osv.dev/vulnerability/CVE-2023-53669

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-53669/
Summaries are generated and may contain mistakes; the official description above is the record.