CVE-2026-46207
MediumCVSS 5.5Exploitation Probability (EPSS)
Low risk2th percentile - higher than 2% of all known CVEs
Summary
A vulnerability has been identified in the Linux kernel related to improper data copying for non-linear buffers. The issue was that during the copying of the original payload to a new buffer, the copy length was set to zero, resulting in no data being copied.
Risk Assessment
The lack of copied data to the monitoring interface may lead to improper functioning of applications using this interface, potentially affecting the stability and security of the system.
Recommendation
It is recommended to update the Linux kernel to the latest version to eliminate this vulnerability and ensure proper data copying for non-linear buffers.
Original NVD description (English source)
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.