CVE-2026-82962: ethernet_fill_header() in subsys/net/l2/ethernet/ethernet.c can prepend the Ethernet header in place, by pushing it into the headroom of the packet's first frag

ethernet_fill_header() in subsys/net/l2/ethernet/ethernet.c can prepend the Ethernet header in place, by pushing it into the headroom of the packet's first frag

ethernet_fill_header() in subsys/net/l2/ethernet/ethernet.c can prepend the Ethernet header in place, by pushing it into the headroom of the packet's first fragment, instead of allocating a separate header fragment. Before this fix the in-place path was selected purely from the build-time value of CONFIG_NET_L2_ETHERNET_RESERVE_HEADER, with no check that the packet actually has that headroom, and then called net_buf_push(pkt->buffer, hdr_len). Only Ethernet TX allocations reserve that space: net_pkt_alloc_buffer() invokes the L2 alloc hook (ethernet_l2_alloc()) only when is_pkt_tx() is true and the packet's interface is the Ethernet interface. A packet that was allocated by a different L2 and then handed to Ethernet for transmission therefore has too little (usually zero) headroom. Such packets are produced by ordinary routing and tunnelling paths: net_route_packet_if() re-targets a received packet to another interface when CONFIG_NET_IPV4_FORWARDING / CONFIG_NET_IPV6_FORWARDING are enabled (for example an 802.15.4/OpenThread or PPP interface forwarding to Wi-Fi/Ethernet), net_route_ipv6_mcast_forward_packet() forwards an RX-slab clone that carries no reserve, and the IPIP tunnel

Description from the National Vulnerability Database, published by vulnerabilities@zephyrproject.org

What it means for a small business

If your business uses zephyr, install the vendor's update. If you're not sure whether you use it, ask whoever manages your computers.

Check your own setup

Website check: reads what your site runs from the outside (WordPress version, plugins it can see, old server software) and matches it against this database.
Server check: what your web server says about itself, and whether that version has known flaws.

Sources

Part of the Huttenlocher Technologies vulnerability database, refreshed twice a day from CISA and the NVD. The title, category and plain-language guidance are ours; check the linked record before acting on a detail. This is general guidance, not a review of your systems.

Weekly security brief

The flaws that hit local websites, every Friday.

One short email: what got exploited this week, which WordPress plugins broke, and what to check. Unsubscribe in one click.