vsock/vmci: validate packet source for connected sockets

In the Linux kernel, the following vulnerability has been resolved: vsock/vmci: validate packet source for connected sockets vmci_transport_recv_stream_cb() looks up sockets first by the full source and destination tuple, then by destination only in the bound table. The fallback can select a non-listening socket without checking whether the packet came from its stored peer. This was reproduced with two VMCI contexts. A RST from the context not stored in a TCP_SYN_SENT socket reset that socket after it was selected by the destination-only lookup. VMCI can process notification packets in bottom-half context when the socket is not owned by user context, or defer packets to a workqueue. Use vsock_check_source() after taking the socket lock in the bottom-half path, and recheck after lock_sock() in the workqueue path. Listening sockets continue to accept packets from any source. Reply with a RST addressed from the received packet before dropping a source that fails validation. This preserves the existing reset behavior for bound non-listening and concurrently closed sockets without directing the reset to a connected socket's stored peer.

Source published

28 Oct 2026 10:34:37 UTC

Source modified

31 Oct 2026 12:43:23 UTC

Observed here

31 Oct 2026 13:33:50 UTC

Source terms

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CVSS 3.1 · 7.3 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:N/A:H