Description
The UpdateHub firmware-update agent's probe handler (z_impl_updatehub_probe() in subsys/mgmt/updatehub/updatehub.c) parses the JSON metadata returned by the update server into a fixed two-level nested-array struct. After parsing it validates only the outer array length (objects_len != 2) and then dereferences objects[1].objects[0].objects.sha256sum via strlen() without checking that the inner object array of element [1] is non-empty.

The metadata is attacker-influenceable network input: the agent fetches it over CoAP from the configured UpdateHub server during its routine OTA probe. A malicious or compromised update server (or, when DTLS is disabled, a network man-in-the-middle) can return a response whose second outer object array is empty. Because the parse target is zero-initialised, the corresponding objects[1].objects[0].objects.sha256sum pointer is NULL, and the subsequent strlen() dereferences address zero. The same defect exists in both the 'any boards' and 'some boards' metadata layouts.

The resulting CPU fault is fatal under Zephyr's default error handling, halting or resetting the device, so the flaw is a remotely triggerable denial of service. Impact is limited to availability; it is a read from NULL with no out-of-bounds write, memory corruption, or information disclosure. The fix rejects metadata whose inner object array is empty before any dereference, on both layouts.
Published: 2026-08-10
Score: 7.5 High
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

Impact

The vulnerability is a NULL-pointer dereference that occurs when the UpdateHub OTA agent parses JSON metadata returned by the update server. The agent validates only the outer array length, then dereferences a pointer derived from the second outer object's inner array without checking that the inner array is non‑empty, leading to a fatal CPU fault. The impact is limited to device availability, as the fault halts or resets the device but does not expose data or allow code execution.

Affected Systems

Zephyr project systems using the UpdateHub firmware‑update agent are affected. The flaw is present in both the 'any boards' and 'some boards' metadata layouts. Affected devices use CoAP to retrieve OTA firmware metadata from a configured UpdateHub server.

Risk and Exploitability

The defect can be triggered remotely by an attacker who controls the UpdateHub server or, if DTLS is disabled, by a network man‑in‑the‑middle. An attacker can send a response where the second outer array is empty, causing the agent to dereference a NULL pointer and crash. The CVSS score of 7.5 indicates a high severity, and while an EPSS score is not currently available, the vulnerability is not listed in CISA KEV, meaning no publicly known exploits have been reported yet. However, the simple nature of the attack and its remote triggerability make it a significant risk for systems that rely on UpdateHub OTA updates.

Generated by OpenCVE AI on August 10, 2026 at 21:32 UTC.

Remediation

No vendor fix or workaround currently provided.

OpenCVE Recommended Actions

  • Upgrade Zephyr to the latest release that includes the UpdateHub metadata validation patch (e.g., the commit 3424082022cb39d568434021b1d6f68b6a7fb3bf).
  • Verify that your UpdateHub server provides well‑formed metadata that includes a non‑empty inner array; consider implementing server‑side validation or using a trusted update channel.
  • If immediate upgrade is not possible, disable OTA updates or block CoAP traffic to the update server until the patch is applied, and enable DTLS for CoAP to mitigate MITM attacks.

Generated by OpenCVE AI on August 10, 2026 at 21:32 UTC.

Tracking

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Advisories

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History

Tue, 11 Aug 2026 15:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Tue, 11 Aug 2026 03:00:00 +0000

Type Values Removed Values Added
First Time appeared Zephyrproject
Zephyrproject zephyr
Vendors & Products Zephyrproject
Zephyrproject zephyr

Mon, 10 Aug 2026 20:45:00 +0000

Type Values Removed Values Added
Description The UpdateHub firmware-update agent's probe handler (z_impl_updatehub_probe() in subsys/mgmt/updatehub/updatehub.c) parses the JSON metadata returned by the update server into a fixed two-level nested-array struct. After parsing it validates only the outer array length (objects_len != 2) and then dereferences objects[1].objects[0].objects.sha256sum via strlen() without checking that the inner object array of element [1] is non-empty. The metadata is attacker-influenceable network input: the agent fetches it over CoAP from the configured UpdateHub server during its routine OTA probe. A malicious or compromised update server (or, when DTLS is disabled, a network man-in-the-middle) can return a response whose second outer object array is empty. Because the parse target is zero-initialised, the corresponding objects[1].objects[0].objects.sha256sum pointer is NULL, and the subsequent strlen() dereferences address zero. The same defect exists in both the 'any boards' and 'some boards' metadata layouts. The resulting CPU fault is fatal under Zephyr's default error handling, halting or resetting the device, so the flaw is a remotely triggerable denial of service. Impact is limited to availability; it is a read from NULL with no out-of-bounds write, memory corruption, or information disclosure. The fix rejects metadata whose inner object array is empty before any dereference, on both layouts.
Title NULL-pointer dereference in UpdateHub OTA agent on empty inner metadata array (remote DoS)
Weaknesses CWE-476
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

Subscriptions

Zephyrproject Zephyr
cve-icon MITRE

Status: PUBLISHED

Assigner: zephyr

Published:

Updated: 2026-08-11T14:32:43.512Z

Reserved: 2026-06-09T15:51:48.612Z

Link: CVE-2026-11810

cve-icon Vulnrichment

Updated: 2026-08-11T14:32:38.024Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-08-10T21:17:19.223

Modified: 2026-08-26T16:59:23.267

Link: CVE-2026-11810

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-08-11T02:45:06Z

Weaknesses