CVE-2026-89725

/// Technical description

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

media: cec: stm32: prevent out-of-bounds write on RX overflow

stm32_rx_done() appends each received CEC byte to rx_msg.msg[] using

rx_msg.len as the write index, incrementing it on every RXBR

(receive-byte-ready) interrupt without checking it against the buffer

size:

cec->rx_msg.msg[cec->rx_msg.len++] = val & 0xFF;

rx_msg.msg[] is a fixed CEC_MAX_MSG_SIZE (16) byte array in struct

cec_msg, and rx_msg.len is only reset on RXACKE/RXOVR or after a

completed message (RXEND). The number of bytes received before RXEND is

decided by the remote CEC device (it sets EOM), not by the driver. A

peer that keeps sending bytes without ending the message drives RXBR

repeatedly, pushing rx_msg.len past 16 and writing peer-controlled bytes

out of bounds into the surrounding memory. This is reachable in normal

operation once the driver has probed and receiving is enabled, from the

IRQ thread, without any local privilege.

The length

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References