CVE-2026-74694

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

net/ncsi: fix heap OOB read in NCSI_CMD_SEND_CMD payload length

ncsi_send_cmd_nl() takes the number of bytes to copy from the

attacker-controlled ncsi_pkt_hdr.length field of the in-band packet

header, while the source buffer is the NCSI_ATTR_DATA netlink

attribute whose readable size is nla_len() - sizeof(ncsi_pkt_hdr).

The two length sources are never cross-checked: only

nla_len() >= sizeof(struct ncsi_pkt_hdr) is enforced.

With hdr->length set larger than the attribute payload (up to 65535

against at most 2032 readable bytes), ncsi_cmd_handler_oem() copies

past the end of the netlink attribute buffer with unsafe_memcpy(),

leaking up to ~64KB of kernel heap memory into the transmitted NCSI

command packet. The destination skb is sized by the declared payload,

so the write side does not overflow - this is a pure OOB read /

information leak, reachable with CAP_NET_ADMIN on systems with a

registered NCSI device (e.g. OpenBMC on Aspeed BMC SoCs, where

NET_NCSI=y is standard).

Reject commands whose declared payload extends past the end of the

data attribute.

The issue was found by the autokbug dynamic kernel fuzzer at Tencent

Yunding Lab.