# CVE-2026-80951

## Summary

- **CVE ID:** CVE-2026-80951
- **Severity:** UNKNOWN
- **CVSS Score:** 1.51
- **CWE:** N/A
- **Published:** Sep 11, 2026
- **Last Modified:** Sep 16, 2026

## Description

In the Linux kernel, the following vulnerability has been resolved:

i3c: master: svc: bound IBI payload to the requested max_payload_len

svc_i3c_master_handle_ibi() reads the IBI payload from the RX FIFO into
the IBI slot. The loop is bounded by the hardware FIFO size
(SVC_I3C_FIFO_SIZE), not by the slot size.

slot->data points into the IBI pool, which i3c_generic_ibi_alloc_pool()
sizes at max_payload_len per slot. svc_i3c_master_request_ibi() only
rejects a max_payload_len larger than SVC_I3C_FIFO_SIZE, so a driver can
request a smaller one. mctp-i3c requests 1. Each readsb() then copies the
controller RXCOUNT bytes (up to 31) with no check against the slot size.
A device that sends more bytes than the slot holds writes past
slot->data, an out-of-bounds write into the IBI pool.

Bound the loop by dev->ibi->max_payload_len and clamp each read to the
space left in the slot, the same way dw-i3c does. A device can still send
more than the requested payload. Flush the leftover bytes from the RX FIFO
so they do not leak into the next transfer.

## Affected Products

- Linux — Linux (dd3c52846d5954acd43f0e771689302f27dadc28)
- Linux — Linux (5.12)
- Linux — Linux (0)
- Linux — Linux (6.12.109)
- Linux — Linux (6.18.50)
- Linux — Linux (7.2.4)
- Linux — Linux (7.3-rc1)
- Linux — Linux (5.15.221)
- Linux — Linux (6.1.188)
- Linux — Linux (6.6.157)

## References

- [CNA](https://git.kernel.org/stable/c/f296a0d5907bf88314dfda67245f7f69d1552470)
- [CNA](https://git.kernel.org/stable/c/5697d779577e2786ff3348ae9b77020ac0cf0aab)
- [CNA](https://git.kernel.org/stable/c/aac3c5aababc7fb69d5bf5b0cc52d308574e3a8c)
- [CNA](https://git.kernel.org/stable/c/e2bda39d7f9f285ec803e200b5c1f17143d0b483)
- [CNA](https://git.kernel.org/stable/c/7c099b0b292a68d0ef558527945dbfb756fbf893)
- [CNA](https://git.kernel.org/stable/c/7cc5ba756bc1cfffab9cb2695742f9f479dc73f7)
- [CNA](https://git.kernel.org/stable/c/35aa6730b8c5626b879a4e893fe664f59bf07d7f)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.21%
- **EPSS Percentile:** 10.8

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-17._