CVE-2026-74694

Summary

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.

Affected Software

Weaknesses

References

• https://git.kernel.org/stable/c/e60afa01d35f8b2671b27ca93309921427144cce
• https://git.kernel.org/stable/c/67c72b8ef63d9d9a610546fda30b116638f39745
• https://git.kernel.org/stable/c/4489b4a17892750131e4bef4bc1d3d703c8fb5ba
• https://git.kernel.org/stable/c/43c7d0a6917751ea898ae584d00f24f5deac46d4
• https://git.kernel.org/stable/c/b5231ad0b376b801ab8cf2962b182cc29deaedb3
• https://git.kernel.org/stable/c/02226af69362758046822840fc6a497f5de33f00
• https://git.kernel.org/stable/c/3a60b5af75abe8e3494ccd074fb4ae6e601a3e55
• https://git.kernel.org/stable/c/afa58b7384913c8773d837acdb07b035690ec5d2

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