# CVE-2026-10672: Unterminated URI buffer causes out-of-bounds read in LwM2M firmware pull (Package URI)

> An attacker can trigger an out-of-bounds read in Zephyr RTOS LwM2M firmware pull, leaking adjacent memory or crashing the device.

- **Severity:** High 8.2 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/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:** 14 Jul 2026
- **Updated:** 15 Oct 2026
- **Also known as:** GHSA-rf6j-4mpp-j9mf

## What is CVE-2026-10672?

CVE-2026-10672 is a high-severity vulnerability in Zephyrproject Zephyr, published on 14 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

subsys/net/lib/lwm2m/lwm2m_pull_context.c copied the firmware-update Package URI into a fixed static buffer (context.uri, size CONFIG_LWM2M_SWMGMT_PACKAGE_URI_LEN, default 128) with memcpy(context.uri, uri, LWM2M_PACKAGE_URI_LEN), copying exactly the destination size with no length validation. The Firmware-Update object stores the server-supplied Package URI (/5/0/1) in a 255-byte buffer, so a LwM2M management server (or an on-path attacker on a session lacking strong DTLS) can WRITE a URI of 128-254 characters; only the first 128 bytes are then copied into context.uri with no NUL terminator. That buffer is subsequently consumed as a C string by http_parser_parse_url(context.uri, strlen(context.uri), ...), strlen-based CoAP URI-path/PROXY-URI option appends, and lwm2m_parse_peerinfo(), causing an out-of-bounds read of adjacent static memory. The over-read bytes are appended to outbound CoAP requests (information disclosure of adjacent device memory to the server/proxy) and can crash the device (denial of service). The vulnerable copy was introduced by the pull-context refactor (first released in v3.0.0) and is present through v4.4.0; the default-on CONFIG_LWM2M_FIRMWARE_UPDATE_PULL_SUPPORT path is affected. The fix adds a strlen(uri) >= sizeof(context.uri) check returning -ENOMEM and switches to strcpy(), guaranteeing a bounded, NUL-terminated buffer.

Weakness: CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2026-10672?

It affects 1 product.


Products: Zephyrproject Zephyr.

## How do I fix CVE-2026-10672?

No fix has been published for CVE-2026-10672 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-10672 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-10672 exists.

Public exploit code:

- https://github.com/Hunt-Benito/zephyr-lwm2m-firmware-update-oob-read-cve-2026-10672-truncated-package-uri (github_poc): https://github.com/Hunt-Benito/zephyr-lwm2m-firmware-update-oob-read-cve-2026-10672-truncated-package-uri

## 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-2026-10672 and fix it if it is affected.

What it is: CVE-2026-10672 is a high-severity vulnerability in Zephyrproject Zephyr, published on 14 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-2026-10672 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-2026-10672/ (Markdown: https://insights.sbomify.com/CVE-2026-10672/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-10672
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-10672
- OSV: https://osv.dev/vulnerability/CVE-2026-10672

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-10672/
Summaries are generated and may contain mistakes; the official description above is the record.