If left unpatched, CVE-2026-82962 could lead to major system disruptions or data loss.
Status: Awaiting Analysis
Published on: 28 Oct 2026, 17:18 UTC
CVSS Release: version 3
vulnerabilities@zephyrproject.org
Secondary
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H
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 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 interface_send() prepends an outer IP header allocated on the virtual interface. In these configurations a remote or adjacent attacker triggers the condition simply by sending traffic that the device forwards. Because net_buf_simple_push() only asserts on the headroom bound, a build without CONFIG_ASSERT (and without the newer CONFIG_NET_BUF_HARDENING) moves the fragment data pointer below the start of its data block and writes 14 bytes — 18 with VLAN — of Ethernet header out of bounds. With the default fixed-size buffer pools this overwrites the tail of the neighbouring buffer's payload or memory preceding the pool array; with variable-size pools it overwrites the buffer reference count and the heap chunk header. The attacker controls neither the written bytes nor the offset, so the practical impact is memory corruption leading to a crash, packet corruption, or heap inconsistency rather than controlled code execution. The fix takes the in-place path only when net_buf_headroom(pkt->buffer) is large enough and otherwise falls back to a separate header fragment.
The exploitability of CVE-2026-82962 depends on two key factors: attack complexity (the level of effort required to execute an exploit) and privileges required (the access level an attacker needs).
CVE-2026-82962 presents a challenge to exploit due to its high attack complexity, but the absence of privilege requirements still makes it a viable target for skilled attackers. A thorough security review is advised.
A lower complexity and fewer privilege requirements make exploitation easier. Security teams should evaluate these aspects to determine the urgency of mitigation strategies, such as patch management and access control policies.
Attack Complexity (AC) measures the difficulty in executing an exploit. A high AC means that specific conditions must be met, making an attack more challenging, while a low AC means the vulnerability can be exploited with minimal effort.
Privileges Required (PR) determine the level of system access necessary for an attack. Vulnerabilities requiring no privileges are more accessible to attackers, whereas high privilege requirements limit exploitation to authorized users with elevated access.
Above is the CVSS Sub-score Breakdown for CVE-2026-82962, illustrating how Base, Impact, and Exploitability factors combine to form the overall severity rating. A higher sub-score typically indicates a more severe or easier-to-exploit vulnerability.
Below is the Impact Analysis for CVE-2026-82962, showing how Confidentiality, Integrity, and Availability might be affected if the vulnerability is exploited. Higher values usually signal greater potential damage.
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