CVE-2026-17051 in Zephyr
Summary
by MITRE • 09/21/2026
The Intel SEDI IPM (inter-processor mailbox) driver in drivers/ipm/ipm_sedi.c handles an inbound message interrupt in ipm_event_dispose(). It read the peer-written doorbell register, extracted the payload length with IPC_HEADER_GET_LENGTH(), and passed that length straight to sedi_ipc_read_msg() to copy the message into struct ipm_sedi_context.incoming_data_buf, without checking it against the buffer size. The doorbell length field is 10 bits wide (IPC_HEADER_LENGTH_MASK is 0x03FF), so it can encode up to 1023 bytes, while incoming_data_buf is IPC_DATA_LEN_MAX (128) bytes. The bounds check in the underlying HAL sedi_ipc_read_msg() is a DBG_CHECK that compiles away unless CONFIG_DEBUG is set, so no check remained in a production image.
The doorbell register is written by the peer processor on the other side of the IPC link — for the intel_ish_5_* targets, the host CPU's ISH driver, reached through the device's memory-mapped register window. Host-side software with driver-level or raw BAR access can therefore set a length of up to 1023 and cause the interrupt handler to copy far past the destination buffer. The affected path requires an application to have registered an IPM receive callback via ipm_register_callback(), which is the driver's normal mode of use.
The result is an out-of-bounds write of up to 895 bytes into static (.bss) memory, performed in interrupt context. The overflow first clobbers the rest of struct ipm_sedi_context — including the k_sem and k_mutex used by the transmit path, whose wait queues contain self-referential list pointers — and then adjacent static data, giving a kernel data-structure corruption and crash primitive. The overflowing bytes are read from registers following the message window, a portion of which are themselves peer-programmable. The fix rejects any doorbell whose encoded length exceeds IPC_DATA_LEN_MAX, logging it and acknowledging the doorbell so the peer is not left waiting.
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Analysis
by VulDB Data Team • 09/21/2026
The Intel SEDI IPM driver contains a critical out-of-bounds write vulnerability within its interrupt handling routine ipm_event_dispose(). This flaw arises from a failure to validate the payload length field extracted from an inbound message before copying data into a fixed-size buffer. The doorbell register, which signals incoming messages from peer processors such as the host CPU's ISH driver on intel_ish_5 targets, contains a ten-bit length field capable of encoding values up to 1023 bytes. However, the destination buffer struct ipm_sedi_context.incoming_data_buf is defined with a maximum size of only 128 bytes via IPC_DATA_LEN_MAX. The underlying hardware abstraction layer function sedi_ipc_read_msg() relies on a debug-only check that compiles away in production builds, leaving no runtime validation to prevent excessive data writes when the driver processes messages under normal operating conditions.
This vulnerability allows an attacker with host-side software access or raw BAR register control to trigger arbitrary kernel memory corruption by writing large length values into the doorbell register and subsequently triggering the interrupt handler. The resulting out-of-bounds write extends up to 895 bytes beyond the allocated buffer, corrupting adjacent static data in the .bss segment. Specifically, the overflow overwrites critical members of struct ipm_sedi_context including kernel synchronization primitives such as k_sem and k_mutex used by the transmit path. These structures contain self-referential list pointers within their wait queues, meaning that corruption of these fields directly compromises kernel integrity and stability rather than merely causing a simple buffer overwrite.
The operational impact is severe, enabling potential denial-of-service through system crashes or arbitrary code execution via heap metadata manipulation if adjacent allocations are affected. The vulnerability aligns with CWE-120 Buffer Copy without Checking Size of Input and CWE-787 Out-of-bounds Write in the Common Weakness Enumeration taxonomy. From a threat modeling perspective utilizing MITRE ATT&CK, this flaw facilitates privilege escalation through kernel memory corruption techniques often associated with T1059 Command and Scripting Interpreter or more specifically local exploitation paths leading to system compromise via T1068 Exploitation for Privilege Escalation when combined with other primitives. The attacker leverages the interrupt context execution environment which operates at ring 0 privileges, bypassing user-space isolation boundaries entirely.
Mitigation strategies involve applying vendor-provided patches that enforce strict bounds checking on incoming message lengths before invocation of data copy routines. System administrators should ensure firmware and driver updates are applied to restrict doorbell length validation against IPC_DATA_LEN_MAX thresholds. Additionally, enabling CONFIG_DEBUG in development environments exposes the latent defensive checks present in lower-level HAL functions, though this is not suitable for production deployments due to performance overhead. Hardening measures include implementing strict input sanitization at all IPC boundaries and utilizing static analysis tools capable of detecting unchecked buffer operations during driver development phases to prevent similar architectural flaws from reaching deployment stages.