# CVE-2026-10637: Zephyr OS use-after-free in IPv6 MLD send path

Source: https://junglewise.ai/threats/cve-2026-10637-zephyr-os-use-after-free-in-ipv6-mld-send-path  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-06-16. Updated: 2026-06-16  
License: CC BY 4.0 with a link back

CVE-2026-10637 · Severity: medium · CVSS 5.9 · Published 2026-06-16

A vulnerability exists in the Zephyr operating system's networking stack, specifically within the IPv6 Multicast Listener Discovery (MLD) component. An attacker on the same local network can send a specially crafted network packet that causes the system to access memory it has already released. This can lead to a system crash (denial of service) or, in rare cases, memory corruption, potentially disrupting the device's ability to communicate or operate reliably.

Technologies: [Zephyr Project Zephyr OS](https://junglewise.ai/threats/technologies/zephyr-os). Vendors: [Zephyr Project](https://junglewise.ai/threats/vendors/zephyr-project).

## Quick answers

**Is CVE-2026-10637 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-10637 being exploited in the wild.

**How severe is CVE-2026-10637?** Medium severity, with a CVSS score of 5.9, published 16 June 2026.

**Which products and versions are affected?** Zephyr Project Zephyr OS >= 1.12.0, <= 4.4.0.

**Is there a fix for CVE-2026-10637?** A patch was published on 2026-06-16: Fix merged into main branch Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-10637 attacked?** It is attacked from the adjacent network, in an operating system.

**Am I affected by CVE-2026-10637?** Check whether you run Zephyr Project Zephyr OS at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A use-after-free vulnerability exists in `subsys/net/ip/ipv6_mld.c:mld_send()`. The function calls `net_pkt_iface(pkt)` to update statistics after `net_send_data(pkt)` has already returned successfully. In the Zephyr network stack, a successful send transfers ownership of the packet to the L2 driver, which may immediately free the object. If `CONFIG_NET_STATISTICS_PER_INTERFACE` is enabled, the subsequent access to the freed packet structure results in a dereference of a stale or NULL interface pointer. This is reachable via the `handle_mld_query()` path when the device processes a valid MLDv2 General Query from an adjacent attacker. The flaw is fixed by caching the interface pointer locally before calling the send function.

## Affected products

- Zephyr Project Zephyr OS >= 1.12.0, <= 4.4.0

## Timeline

- 2026-06-16: disclosed
- 2026-06-16: advisory: GHSA-m23w-34pp-4h92 published
- 2026-06-16: patched: Fix merged into main branch

## References

- [https://github.com/zephyrproject-rtos/zephyr/commit/3159c53e8e7d233c2a85a0798cf25ac441db6dae](https://github.com/zephyrproject-rtos/zephyr/commit/3159c53e8e7d233c2a85a0798cf25ac441db6dae)
- [https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-m23w-34pp-4h92](https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-m23w-34pp-4h92)

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