CVE-2026-11810
HighCVSS 7.5Exploitation Probability (EPSS)
Low risk25th percentile - higher than 25% of all known CVEs
Summary
A flaw was found in the UpdateHub firmware-update agent's probe handler that parses JSON metadata from the update server into a fixed two-level nested-array struct. It validates only the outer array length and then dereferences objects[1].objects[0].objects.sha256sum via strlen() without checking that the inner object array is non-empty. A malicious or compromised update server (or a man-in-the-middle when DTLS is disabled) can return a response with an empty inner array, leading to a NULL pointer dereference and a CPU fault, causing a denial of service. The flaw is remotely triggerable and limited to availability.
Risk Assessment
The risk includes remote denial of service, potentially leading to device unavailability and disruption of operations.
Recommendation
Update UpdateHub to a patched version that rejects metadata with an empty inner object array before any dereference, and enable DTLS to secure communication.
Original NVD description (English source)
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.