---
id: CVE-2026-10637
title: >-
  Use-after-free of `net_pkt` in IPv6 MLD send path triggerable by a link-local
  MLD Query
summary: >-
  subsys/net/ip/ipv6_mld.c:mld_send() read the packet interface via
  net_pkt_iface(pkt) after net_send_data(pkt) returned successfully. Per the
  network stack's ownership contract (include/zephyr/net/net_core.h, and the
  explicit warning in s…
severity: medium
cvss: 5.9
cvssVector: 'CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H'
cvssSource: cna
cwe:
  - CWE-416
vendor: zephyrproject
product: zephyr
affected:
  - zephyr >= 1.12.0 < 4.3.1
  - zephyr >= 4.4.0 < 4.4.1
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-06-16T15:30:13.376607Z'
published: '2026-06-16'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T22:10:01.063Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-10637'
references:
  - url: >-
      https://github.com/zephyrproject-rtos/zephyr/commit/3159c53e8e7d233c2a85a0798cf25ac441db6dae
    label: Fix commit
  - url: >-
      https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-m23w-34pp-4h92
    label: GHSA-m23w-34pp-4h92
tags:
  - cve.org
epss: 0.00299
epssPercentile: 0.21045
ingestedAt: '2026-10-15T22:48:25.564Z'
---

## Overview

subsys/net/ip/ipv6_mld.c:mld_send() read the packet interface via net_pkt_iface(pkt) after net_send_data(pkt) returned successfully. Per the network stack's ownership contract (include/zephyr/net/net_core.h, and the explicit warning in subsys/net/ip/net_core.c:453-460 'do not use pkt after that call'), a successful send transfers ownership of the net_pkt and the L2 driver frees it (e.g. ethernet_send() unrefs the packet on success, subsys/net/l2/ethernet/ethernet.c:790), returning it to its k_mem_slab.

The subsequent net_pkt_iface(pkt) is therefore a read of a freed object; the recovered interface pointer is then dereferenced and incremented by the per-interface statistics path (net_stats.h UPDATE_STAT/SET_STAT) when CONFIG_NET_STATISTICS_PER_INTERFACE is enabled. If the freed slot is concurrently reallocated, pkt->iface may read back as NULL (NULL-pointer dereference / crash) or as a stale/garbage pointer (stray increment write / memory corruption).

The path is reachable remotely on the local link without authentication: handle_mld_query() (registered for NET_ICMPV6_MLD_QUERY) responds to a valid MLDv2 General Query (unspecified multicast address, hop limit 1) by calling send_mld_report() -> mld_send().

The result is a remotely triggerable denial of service of the networking stack, with a narrow possibility of memory corruption. The fix caches the interface in a local before sending and no longer touches the packet after net_send_data(). The IPv4/IGMP sibling (igmp_send) already used the corrected pattern.

## Affected

- `zephyr >= 1.12.0 < 4.3.1`
- `zephyr >= 4.4.0 < 4.4.1`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.