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

Status: published. Published: 2026-07-14. Updated: 2026-11-04.

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.

## Remediation

- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: zephyr) — https://github.com/zephyrproject-rtos/zephyr/commit/99a164df5cea5af76e32b57c6d51854f018969a2
- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: vulnerabilities@zephyrproject.org) — https://github.com/zephyrproject-rtos/zephyr/commit/99a164df5cea5af76e32b57c6d51854f018969a2
- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: vulnerabilities@zephyrproject.org) — https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-rf6j-4mpp-j9mf
- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: 134c704f-9b21-4f2e-91b3-4a467353bcc0) — https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-rf6j-4mpp-j9mf

## Affected products and versions

- zephyrproject / zephyr (zephyr): ≥ 3.0.0; < 4.6.0 (affected, semver). Source: CNA: zephyr

## NVD configuration conditions

Affected CPE matches depend on the following AND/OR and negation conditions:

```json
[
  {
    "negate": false,
    "nodes": [
      {
        "cpeMatch": [
          {
            "criteria": "cpe:2.3:o:zephyrproject:zephyr:3.7.1:*:*:*:*:*:*:*",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:o:zephyrproject:zephyr:4.2.1:*:*:*:*:*:*:*",
            "vulnerable": true
          },
          {
            "criteria": "cpe:2.3:o:zephyrproject:zephyr:4.3.0:*:*:*:*:*:*:*",
            "vulnerable": true
          }
        ],
        "negate": false,
        "operator": "OR"
      }
    ],
    "operator": "OR"
  }
]
```

## Severity and prioritization

- CVSS 3.1: 8.2 (high); CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:L; source: CNA: zephyr

- CVSS 3.1: 9.1 (critical); CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H; source: NVD: nvd@nist.gov

- CVSS 3.1: 8.2 (high); CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:L; source: NVD: vulnerabilities@zephyrproject.org

- CISA KEV: No listing in collected sources

- EPSS: 0.58% as of 2026-11-03; percentile 47.68%

- SSVC: exploitation poc; automatable yes; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-125

## Exploit evidence

- exploit: https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-rf6j-4mpp-j9mf (ADP: CISA-ADP)
- exploit: https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-rf6j-4mpp-j9mf (vulnerabilities@zephyrproject.org)
- exploit: https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-rf6j-4mpp-j9mf (134c704f-9b21-4f2e-91b3-4a467353bcc0)

## References

- https://github.com/zephyrproject-rtos/zephyr/commit/99a164df5cea5af76e32b57c6d51854f018969a2 (CNA: zephyr; patch)

- https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-rf6j-4mpp-j9mf (CNA: zephyr)

- https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-rf6j-4mpp-j9mf (ADP: CISA-ADP; exploit)

- https://github.com/zephyrproject-rtos/zephyr/commit/99a164df5cea5af76e32b57c6d51854f018969a2 (vulnerabilities@zephyrproject.org; Patch)

- https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-rf6j-4mpp-j9mf (vulnerabilities@zephyrproject.org; Exploit, Mitigation, Patch, Vendor Advisory)

- https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-rf6j-4mpp-j9mf (134c704f-9b21-4f2e-91b3-4a467353bcc0; Exploit, Mitigation, Patch, Vendor Advisory)

## Provenance

- CNA: zephyr: https://www.cve.org/CVERecord?id=CVE-2026-10672; retrieved 2026-11-04; source updated 2026-11-04

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-10672; retrieved 2026-11-04; source updated 2026-11-04

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-10672; retrieved 2026-11-04; source updated Not reported

Revision: 35510c31adb02847866868029ce91fdadc5d0a96063aeb1123f3616ea2b56cca

Canonical: https://y2.dev/cve/CVE-2026-10672

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