{"id":"CVE-2026-74684","aliases":[],"url":"https://o3.security/vulnerability/CVE-2026-74684","summary":"net: tap: set skb->dev before parsing virtio net header in tap_get_user_xdp()","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: tap: set skb->dev before parsing virtio net header in tap_get_user_xdp()\n\nThe commit 4f61f133f354 (\"net: tap: NULL pointer derefence in\ndev_parse_header_protocol when skb->dev is null\") fixed a crash in\ntap_get_user() by assigning skb->dev before calling tun_vnet_hdr_to_skb().\nThis is required because virtio_net_hdr_to_skb() may invoke\ndev_parse_header_protocol(), which dereferences skb->dev. Without the\nassignment, a NULL pointer dereference can occur.\n\nHowever, tap_get_user_xdp() still parses the virtio-net header before\nassigning skb->dev. When the vhost TX path passes an XDP buffer containing\na GSO virtio-net header but the protocol is set to zero on purpose,\ntun_vnet_hdr_to_skb() can reach dev_parse_header_protocol() while skb->dev\nis still NULL, resulting in a crash.\n\nFix this by looking up the tap device and assigning skb->dev before calling\ntun_vnet_hdr_to_skb(), matching the ordering already used in\ntap_get_user(). Preserve the existing RCU read-side critical section across\ndev_queue_xmit().","published":"2026-08-22T15:32:50.846Z","modified":"2026-08-25T03:51:38.392066423Z","cvss":null,"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"Linux","name":"Kernel","fixedVersion":"6.12.105"}],"fix":null,"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/15583b07fd691a844fbf7b3ad612cdc9e9a657c0"},{"type":"WEB","url":"https://git.kernel.org/stable/c/164c31ee252ebd1ac8f44c2dfc5486b6d9a0379b"},{"type":"WEB","url":"https://git.kernel.org/stable/c/3874892dd27d5387aa9a06f58d9060f18f351d24"},{"type":"WEB","url":"https://git.kernel.org/stable/c/8b444b126cd8e4473e652f529753ed4dd1360a9c"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74684.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-74684"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-25T03:51:38.392066423Z"}}