CVE-2026-80906

A flaw was found in the Linux kernel's network packet processing subsystem. This vulnerability arises when the kernel handles Virtual Local Area Network (VLAN) tagged frames, causing it to incorrectly identify the transport layer header. This misidentification is due to an ordering issue during the packet header parsing process. Consequently, network packets may be processed improperly, potentially leading to unexpected network behavior or communication failures.

AF_PACKET can leave skb transport_header unset for VLAN tagged SOCK_RAW GSO frames because skb_probe_transport_header runs after skb_set_network_header moves network_header past the VLAN header while skb protocol still names the outer VLAN EtherType. The flow dissector then reads the inner protocol header as a VLAN header, fails to identify the transport protocol, and leaves the transport header at the unset sentinel value. For the CVSS the PR:L is used because triggering requires a local process with permission to create AF_PACKET raw sockets, usually CAP_NET_RAW or an equivalent delegated capability. The issue is not directly network reachable because the attacker must inject frames through a local packet socket on the target. Impact is primarily denial of service or packet processing failure, and the paranoid score treats later use of the unset transport header by networking offload or checksum paths as a plausible kernel crash risk.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.