CVE-2026-46207: vsock/virtio: fix empty payload in tap skb for non-linear buffers

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-05-28 · updated 2026-06-17
Weakness: CWE-401

Description

In the Linux kernel, the following vulnerability has been resolved: vsock/virtio: fix empty payload in tap skb for non-linear buffers For non-linear skbs, virtio_transport_build_skb() goes through virtio_transport_copy_nonlinear_skb() to copy the original payload in the new skb to be delivered to the vsockmon tap device. This manually initializes an iov_iter but does not set iov_iter.count. Since the iov_iter is zero-initialized, the copy length is zero and no payload is actually copied to the monitor interface, leaving data un-initialized. Fix this by removing the linear vs non-linear split and using skb_copy_datagram_iter() with iov_iter_kvec() for all cases, as vhost-vsock already does. This handles both linear and non-linear skbs, properly initializes the iov_iter, and removes the now unused virtio_transport_copy_nonlinear_skb(). While touching this code, let's also check the return value of skb_copy_datagram_iter(), even though it's unlikely to fail.

Affected products

Linux kernel: from 6.7 before 6.12.90; from 6.13 before 6.18.32; from 6.19 before 7.0.9; 7.1-rc1, 7.1-rc2, 7.1-rc3 — fixed in 6.12.90, 6.18.32, 7.0.9

How to fix

Upgrade to a fixed version: Linux kernel 6.12.90, 6.18.32, 7.0.9. Check the vendor advisory for mitigations.

References

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