CVE-2026-99123

Status: UPDATED  |  Advisory ID: CVE-2026-99123

Key Details

Affected Products, Subsystems & Sectors

What to Know

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

vsock/virtio: validate packet source for connected sockets

virtio_transport_recv_pkt() looks up sockets first by the full source and

destination tuple, then by destination only in the bound table. The

fallback is needed for listening and connecting sockets, but sockets remain

in the bound table after connect(), so it can also return a non-listening

socket.

The fallback does not validate the source address. In TCP_SYN_SENT, a

RESPONSE from an unrelated source can transition the victim socket to

TCP_ESTABLISHED while its stored remote address remains unchanged.

Subsequent RW packets from that source are delivered through the same

destination-only fallback.

This was reproduced with capability-empty processes under different UIDs.

The attacker discovered the target tuple through unprivileged AF_VSOCK

sock_diag and caused the victim socket to read 16 attacker-chosen bytes;

the intended peer-side socket read 0 of those 16 bytes.

Add vsock_check_source() to validate the transport, source port and source

CID against the peer stored in a non-listening socket. The local transport

is the CID exception because its packets are generated internally with

VMADDR_CID_LOCAL as their source, including connections using CID aliases.

Use the helper after lock_sock() in the virtio receive path. (NVD)

What to Do

Monitor Linux's web page for any future patch releases.

References