---
id: CVE-2026-10636
title: Use-after-free in Zephyr IPv4 IGMP send path (`igmp_send`)
summary: >-
  In Zephyr's IPv4 IGMP implementation, igmp_send() in subsys/net/ip/igmp.c read
  the network interface back out of the packet via net_pkt_iface(pkt) after the
  packet had been handed to net_send_data(). On the successful-send path the
  packe…
severity: low
cvss: 3.7
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L'
cvssSource: cna
cwe:
  - CWE-416
vendor: zephyrproject
product: zephyr
affected:
  - zephyr >= 2.6.0 < 4.3.1
  - zephyr >= 4.4.0 < 4.4.1
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-06-16T15:30:53.213579Z'
published: '2026-06-16'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T22:10:00.580Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-10636'
references:
  - url: >-
      https://github.com/zephyrproject-rtos/zephyr/commit/0223e5e3ec5ebc51e8d0328fc3e604fa43552f54
    label: Fix commit
  - url: >-
      https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-fj6q-975v-65c9
    label: GHSA-fj6q-975v-65c9
tags:
  - cve.org
epss: 0.00308
epssPercentile: 0.22001
ingestedAt: '2026-10-15T22:48:25.565Z'
---

## Overview

In Zephyr's IPv4 IGMP implementation, igmp_send() in subsys/net/ip/igmp.c read the network interface back out of the packet via net_pkt_iface(pkt) after the packet had been handed to net_send_data(). On the successful-send path the packet's last reference may already have been released by the L2 driver or by the network stack's TX handling (synchronously in the default NET_TC_TX_COUNT=0 immediate-transmit configuration), returning the net_pkt slab block to its free list. The subsequent net_pkt_iface(pkt) dereferences the freed packet, a use-after-free read; with CONFIG_NET_STATISTICS_PER_INTERFACE the resulting dangling interface pointer is further dereferenced for a statistics-counter write.

The IGMP send path is reachable without authentication from inbound IPv4 IGMP membership queries addressed to 224.0.0.1 (net_ipv4_igmp_input -> send_igmp_report/send_igmp_v3_report -> igmp_send), as well as from local multicast join/leave/rejoin operations.

Realistic impact is undefined behavior and potential denial of service (sporadic crash or stats corruption); a controllable write requires the asynchronous TX path plus a concurrent slab reuse.

The flaw was introduced with IGMPv2 support and affects releases from v2.6.0 through v4.4.0. The fix caches the interface pointer before sending. Note the analogous IPv6 MLD path (mld_send in subsys/net/ip/ipv6_mld.c) retains the same unfixed pattern.

## Affected

- `zephyr >= 2.6.0 < 4.3.1`
- `zephyr >= 4.4.0 < 4.4.1`

## Remediation

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