PT-2026-62125 · Zephyrproject · Zephyr
CVE-2026-10678
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Published
2026-07-21
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Updated
2026-07-21
CVSS v3.1
8.1
High
| Vector | AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H |
The MCTP-over-I2C+GPIO target binding in Zephyr (subsys/pmci/mctp/mctp i2c gpio target.c) processes pseudo-register writes from an I2C bus master byte-by-byte in mctp i2c gpio target write received() without validating the order or the receive buffer. In the affected versions the MCTP I2C GPIO RX MSG ADDR (data) handler dereferences and writes through b->rx pkt without checking that the receive buffer was allocated: a controller that selects the data register and writes a byte without first sending the length register (which is what allocates the buffer) causes a write of an attacker-chosen byte through a NULL/unallocated mctp pktbuf pointer (i.e. into a small attacker-advanceable offset above address 0), producing memory corruption or a hard fault.
The same handler also performs a write-then-check bounds test, allowing a one-byte heap overflow at data[255] when more than 255 data bytes are sent.
Because the I2C target callback is invoked with raw bytes supplied by whatever device is the bus master and the binding performs no authentication, a malicious or malfunctioning controller on the bus can trigger these without any prior protocol state, leading to memory corruption and/or denial of service on the target device.
The vulnerable code was introduced when the I2C+GPIO target binding was added and shipped in Zephyr v4.3.0 and v4.4.0. The fix defers allocation to the first data byte with a NULL check, treats a missing length as a zero-sized packet rejected by libmctp, and moves the bounds check before the store.
Fix
NULL Pointer Dereference
Memory Corruption
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Related Identifiers
Affected Products
Zephyr