CVE-2026-18418
Received
Received - Intake
Stack-based Buffer Overread in Zephyr RTOS zbus Proxy Agent
Vulnerability report for CVE-2026-18418, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.
Publication date: 2026-10-11
Last updated on: 2026-10-11
Assigner: Zephyr Project
Description
Description
The zbus proxy agent IPC backend in subsys/zbus/proxy_agent/zbus_proxy_agent_ipc.c logged the channel name of a rejected inter-domain frame with a plain %s conversion. The frame type struct zbus_proxy_msg carries a fixed-size channel_name[] array as its last member, and nothing in the transport guarantees the array is NUL-terminated. The only code that verifies termination is zbus_proxy_agent_receive_cb() in subsys/zbus/proxy_agent/zbus_proxy_agent.c, which rejects the frame in precisely those cases — so the warning printed a non-terminated buffer exactly on the error paths where the name had been found invalid (or, for an invalid message_size, had not been inspected at all).
Any peer domain able to place a frame of sizeof(struct zbus_proxy_msg) bytes on the bound ipc_service endpoint can trigger it, by sending a frame with an out-of-range message_size or with channel_name[] containing no NUL byte. Reaching the code requires CONFIG_ZBUS_PROXY_AGENT_IPC and logging built at warning level or above (the default), and requires control over the firmware of the peer domain — typically a second core on the same SoC.
The resulting strlen() inside the log packager walks past the end of the frame object until it finds a zero byte. With the icmsg backend the frame lives in a stack buffer of the IPC work-queue thread, so bytes of that thread's stack are rendered into the log message; with the rpmsg backends the scan continues through the shared vring memory. Impact is bounded to disclosure of a small amount of adjacent memory into the receiving domain's log sink, plus a possible fatal fault if the scan leaves a mapped region; the log packager's own -ENOSPC bound prevents the overrun from becoming a write. The fix bounds the conversion with %.*s and MIN(msg->channel_name_len, sizeof(msg->channel_name)).
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| zephyrproject | zephyr | 4.4.0 |
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-125 | The product reads data past the end, or before the beginning, of the intended buffer. |
