CVE-2026-13217

NULL-pointer dereference in Zephyr OCPP CALLRESULT parsing via unchecked strtok_r/atoi

Published Aug 25, 2026 CVSS 3.1 · 5.9 Medium EPSS < 1% KEV · Not listed
Description
The OCPP 1.6 client in subsys/net/lib/ocpp/ocpp.c reconstructs a session handle and PDU id from the uid field of a CALLRESULT message. In ocpp_process_server_msg() the code calls atoi(strtok_r(uid, "-", &tmp)) without checking the strtok_r return value. When the server-supplied uid is empty or contains no - delimiter, strtok_r() returns NULL and atoi(NULL) dereferences a NULL pointer, which is undefined behaviour.

The uid originates from network data: parse_rpc_msg() in subsys/net/lib/ocpp/ocpp_j.c JSON-parses a frame received from the OCPP central system over TCP/WebSocket and copies the server-controlled string into the local buffer. A malicious or compromised central system, or a man-in-the-middle on a non-TLS ws:// connection, can return a malformed uid to reach the defect. No authentication beyond the existing server connection (or MITM position) is required, and the reconstructed pointer is membership-validated by ocpp_session_is_valid(), so the impact is limited to the NULL dereference rather than arbitrary pointer use.

On Zephyr targets that trap access to address 0 (MMU/MPU platforms or CONFIG_NULL_POINTER_EXCEPTION_DETECTION), the dereference faults inside the OCPP reader thread and invokes the fatal handler, producing a remote denial of service of the charge point; on bare targets where address 0 is readable the call returns 0 and is benign, so the impact is availability-only and platform-conditional.

The applied fix guards only the first atoi(); the second strtok_r(NULL, "-", &tmp) followed by pdu = atoi(buf) in the same function remains unguarded and the identical NULL dereference is still reachable from the same network input when the uid has a first token but no second --delimited token. A complete fix should validate the second token as well.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

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History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Zephyrproject
Zephyrproject zephyr
Vendors & Products Zephyrproject
Zephyrproject zephyr
Type Values Removed Values Added
Description The OCPP 1.6 client in subsys/net/lib/ocpp/ocpp.c reconstructs a session handle and PDU id from the uid field of a CALLRESULT message. In ocpp_process_server_msg() the code calls atoi(strtok_r(uid, "-", &tmp)) without checking the strtok_r return value. When the server-supplied uid is empty or contains no - delimiter, strtok_r() returns NULL and atoi(NULL) dereferences a NULL pointer, which is undefined behaviour. The uid originates from network data: parse_rpc_msg() in subsys/net/lib/ocpp/ocpp_j.c JSON-parses a frame received from the OCPP central system over TCP/WebSocket and copies the server-controlled string into the local buffer. A malicious or compromised central system, or a man-in-the-middle on a non-TLS ws:// connection, can return a malformed uid to reach the defect. No authentication beyond the existing server connection (or MITM position) is required, and the reconstructed pointer is membership-validated by ocpp_session_is_valid(), so the impact is limited to the NULL dereference rather than arbitrary pointer use. On Zephyr targets that trap access to address 0 (MMU/MPU platforms or CONFIG_NULL_POINTER_EXCEPTION_DETECTION), the dereference faults inside the OCPP reader thread and invokes the fatal handler, producing a remote denial of service of the charge point; on bare targets where address 0 is readable the call returns 0 and is benign, so the impact is availability-only and platform-conditional. The applied fix guards only the first atoi(); the second strtok_r(NULL, "-", &tmp) followed by pdu = atoi(buf) in the same function remains unguarded and the identical NULL dereference is still reachable from the same network input when the uid has a first token but no second --delimited token. A complete fix should validate the second token as well.
Title NULL-pointer dereference in Zephyr OCPP CALLRESULT parsing via unchecked strtok_r/atoi
Weaknesses CWE-476
References
Metrics cvssV3_1

{'score': 5.9, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
zephyr
Published
Updated
Nov 4, 2026, 4:59 AM
Reserved
Jun 24, 2026, 3:29 PM
Status
Awaiting Analysis
Published
Aug 25, 2026, 5:17 PM
Modified
Nov 4, 2026, 5:18 AM