CVE-2026-74684

Technical Description

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

net: tap: set skb->dev before parsing virtio net header in tap_get_user_xdp()

The commit 4f61f133f354 ("net: tap: NULL pointer derefence in

dev_parse_header_protocol when skb->dev is null") fixed a crash in

tap_get_user() by assigning skb->dev before calling tun_vnet_hdr_to_skb().

This is required because virtio_net_hdr_to_skb() may invoke

dev_parse_header_protocol(), which dereferences skb->dev. Without the

assignment, a NULL pointer dereference can occur.

However, tap_get_user_xdp() still parses the virtio-net header before

assigning skb->dev. When the vhost TX path passes an XDP buffer containing

a GSO virtio-net header but the protocol is set to zero on purpose,

tun_vnet_hdr_to_skb() can reach dev_parse_header_protocol() while skb->dev

is still NULL, resulting in a crash.

Fix this by looking up the tap device and assigning skb->dev before calling

tun_vnet_hdr_to_skb(), matching the ordering already used in

tap_

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