# CVE-2026-10636: Use-after-free in Zephyr IPv4 IGMP send path (`igmp_send`)

> Remote attackers can trigger a use-after-free in Zephyr's IGMP implementation via crafted queries, causing crashes or denial of service.

- **Severity:** Low 3.7 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 16 Jun 2026
- **Updated:** 15 Oct 2026
- **Also known as:** GHSA-fj6q-975v-65c9

## What is CVE-2026-10636?

CVE-2026-10636 is a low-severity use after free vulnerability in Zephyrproject Zephyr, published on 16 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

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.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2026-10636?

It affects 1 product.


Products: Zephyrproject Zephyr.

## How do I fix CVE-2026-10636?

No fix has been published for CVE-2026-10636 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-10636 being exploited?

There is no known exploitation of CVE-2026-10636 in the wild and no public exploit code.

## Other vulnerabilities in Zephyrproject Zephyr

- [CVE-2026-5067](https://insights.sbomify.com/CVE-2026-5067/): Out-of-bounds read/write in HTTP WebSocket upgrade via non-null-terminated Sec-WebSocket-Key (critical 9.8)
- [CVE-2022-3806](https://insights.sbomify.com/CVE-2022-3806/): Bluetooth HCI Error Handling Double Free (critical 9.8)
- [CVE-2017-14199](https://insights.sbomify.com/CVE-2017-14199/): Memory corruption in getaddrinfo (critical 9.8)
- [CVE-2018-1000800](https://insights.sbomify.com/CVE-2018-1000800/): Null dereference in n/a (critical 9.8)
- [CVE-2021-3329](https://insights.sbomify.com/CVE-2021-3329/): DOS: Incorrect handling of the initial HCI ACL_MTU handshake packet leads to crash of bluetooth host layer (critical 9.6)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-10636 and fix it if it is affected.

What it is: CVE-2026-10636 is a low-severity use after free vulnerability in Zephyrproject Zephyr, published on 16 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-10636 in the wild and no public exploit code.

Affected product: Zephyrproject Zephyr. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-10636/ (Markdown: https://insights.sbomify.com/CVE-2026-10636/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-10636
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-10636
- OSV: https://osv.dev/vulnerability/CVE-2026-10636

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-10636/
Summaries are generated and may contain mistakes; the official description above is the record.