CVE-2026-11810: zephyr NULL Pointer Dereference (CVSS 7.5)

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.

Metrics

CVSS 3.1

7.5/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS Probability

0.47%

40.5th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-476

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

Vendor	Product	Versions
zephyrproject	zephyr	>= 3.7.0, < 4.3.2; >= 4.4.0, < 4.4.2

References

Timeline

Published: Aug 10, 2026
Last Modified: Nov 4, 2026
Status: Awaiting Analysis

Frequently Asked Questions

What is CVE-2026-11810?

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.

How severe is CVE-2026-11810?

CVE-2026-11810 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 0.47% probability of exploitation in the next 30 days.

How do I fix CVE-2026-11810?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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