CVE-2026-64450

Technical Description

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

tipc: fix out-of-bounds read in broadcast Gap ACK blocks

A broadcast PROTOCOL/STATE_MSG can carry a Gap ACK blocks record in its

data area. tipc_get_gap_ack_blks() only verifies that the record's len

field is self-consistent with its ugack_cnt/bgack_cnt counts

(sz == struct_size(p, gacks, ugack_cnt + bgack_cnt)); it does not check

that the record actually fits in the message data area, msg_data_sz().

The unicast caller tipc_link_proto_rcv() bounds it ("if (glen > dlen)

break;"), but the broadcast caller tipc_bcast_sync_rcv() discards the

returned size, so tipc_link_advance_transmq() copies the record off the

receive skb with an attacker-controlled count:

this_ga = kmemdup(ga, struct_size(ga, gacks, ga->bgack_cnt),

GFP_ATOMIC);

A TIPC neighbour that negotiated TIPC_GAP_ACK_BLOCK triggers it with one

ordinary broadcast STATE_MSG (msg_bc_ack_invalid() clear), sized so its

data area is short, carrying a Gap ACK

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