CVE-2026-80906
Description
In the Linux kernel, the following vulnerability has been resolved: net: packet: fix wrong transport_header when sending VLAN-tagged frame In packet_parse_headers(), when processing a VLAN-tagged frame, skb_set_network_header() is called to advance network_header past the VLAN tag to the inner protocol header. skb_probe_transport_header() is then called with skb->protocol still set to the outer VLAN EtherType (e.g. ETH_P_8021Q), while nhoff (derived from skb_network_offset()) already points past the VLAN tag to the inner protocol header. In __skb_flow_dissect(), proto is initialized to ETH_P_8021Q and nhoff points past the VLAN tag. When the dissector hits case ETH_P_8021Q, it reads a struct vlan_hdr at nhoff via __skb_header_pointer(), but that offset contains the inner protocol header (e.g. an IP header). The bytes are misinterpreted as a VLAN header, yielding a garbage encapsulated EtherType that matches no known protocol. The dissector returns false, so skb_probe_transport_header() never calls skb_set_transport_header(), leaving transport_header at its uninitialized sentinel value (~0U). Move skb_probe_transport_header() to before skb_set_network_header(). At the time skb_probe_transport_header() is called, network_header still points to the VLAN header, so nhoff correctly points to the VLAN header. The flow dissector can then parse the VLAN header, extract the inner EtherType, and advance nhoff to the inner protocol header, allowing transport_header to be set correctly.
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
No mitigations published for this CVE yet.
The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.
Propose a mitigation on Community Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here withsource_tier=community-verified.
References
- https://git.kernel.org/stable/c/01fdecc0480d916c799dbee584833a4a37e94d06
- https://git.kernel.org/stable/c/5479eb9b355f44745d7ccfe112386bd4f96eceea
- https://git.kernel.org/stable/c/6386a6ffa2efba2965ed8e4fa303582c0b76a215
- https://git.kernel.org/stable/c/6971cf319263d6a1b4096f9248aca9e57d77a1eb
- https://git.kernel.org/stable/c/a4b82de96d465ddb44bc931145c0fa80c4fe9c9c
- https://git.kernel.org/stable/c/e451e20adb869a983a21dda158625f024142e61f
- https://git.kernel.org/stable/c/f9297abbcaba760b7a7b9d63b839f607f738013e
- https://git.kernel.org/stable/c/fa86bc52ea8ba981f74f851fd61e2a3d3bc0feac
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.