# CVE-2026-10665: Heap buffer overflow on WireGuard receive path via unbounded incoming packet length

> Remote attackers can trigger heap buffer overflow in Zephyr's WireGuard implementation via oversized packets, causing denial of service or potential code execution.

- **Severity:** High 7.4 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 12 Jul 2026
- **Updated:** 15 Oct 2026
- **Also known as:** GHSA-3wqm-wgx2-9367

## What is CVE-2026-10665?

CVE-2026-10665 is a high-severity memory corruption vulnerability in Zephyrproject Zephyr, published on 12 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

In Zephyr's WireGuard subsystem (subsys/net/lib/wireguard), wg_process_data_message() in wg_crypto.c linearizes an inbound transport-data payload into a fixed pool buffer of CONFIG_WIREGUARD_BUF_LEN bytes before decryption. The call net_buf_linearize(buf->data, data_len, pkt->buffer, ..., data_len) passed the attacker-derived data_len as both the destination capacity and the copy length, defeating the function's internal len = min(len, dst_len) bound. data_len is derived from the received UDP datagram length and is only lower-bounded by wg_ctrl_recv() (no upper bound). When data_len exceeds CONFIG_WIREGUARD_BUF_LEN — e.g. when the buffer length is lowered below the link MTU, on links with MTU above the buffer size, or via reassembled IPv4/IPv6 fragments that exceed it — the underlying memcpy writes past the end of the pool buffer, an out-of-bounds write (CWE-787). The overflow occurs before the Poly1305 authentication check, so it requires only a valid receiver session index rather than a valid authenticator, and is reachable by a malicious or compromised peer (or an on-path attacker driving an established session) over the network, yielding remote memory corruption and at minimum a reliable denial of service. The defect was present in the WireGuard implementation shipped in Zephyr 4.4.0. The fix adds an explicit data_len > CONFIG_WIREGUARD_BUF_LEN rejection and corrects the linearize call to pass net_buf_max_len(buf) as the destination capacity.

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2026-10665?

It affects 1 product.


Products: Zephyrproject Zephyr.

## How do I fix CVE-2026-10665?

No fix has been published for CVE-2026-10665 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-10665 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-10665 exists.

## 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-2026-10665 and fix it if it is affected.

What it is: CVE-2026-10665 is a high-severity memory corruption vulnerability in Zephyrproject Zephyr, published on 12 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-10665 exists.

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-2026-10665/ (Markdown: https://insights.sbomify.com/CVE-2026-10665/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-10665
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-10665
- OSV: https://osv.dev/vulnerability/CVE-2026-10665

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-10665/
Summaries are generated and may contain mistakes; the official description above is the record.