CVE-2025-38413 in Linux
Summary
by MITRE • 07/25/2025
In the Linux kernel, the following vulnerability has been resolved:
virtio-net: xsk: rx: fix the frame's length check
When calling buf_to_xdp, the len argument is the frame data's length without virtio header's length (vi->hdr_len). We check that len with
xsk_pool_get_rx_frame_size() + vi->hdr_len
to ensure the provided len does not larger than the allocated chunk size. The additional vi->hdr_len is because in virtnet_add_recvbuf_xsk, we use part of XDP_PACKET_HEADROOM for virtio header and ask the vhost to start placing data from
hard_start + XDP_PACKET_HEADROOM - vi->hdr_len not hard_start + XDP_PACKET_HEADROOM
But the first buffer has virtio_header, so the maximum frame's length in the first buffer can only be
xsk_pool_get_rx_frame_size() not xsk_pool_get_rx_frame_size() + vi->hdr_len
like in the current check.
This commit adds an additional argument to buf_to_xdp differentiate between the first buffer and other ones to correctly calculate the maximum frame's length.
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Analysis
by VulDB Data Team • 01/03/2026
The vulnerability CVE-2025-38413 addresses a critical flaw in the Linux kernel's virtio-net implementation that affects the XDP (eXpress Data Path) packet processing mechanism. This issue specifically impacts the rx (receive) path of virtio network devices when using XDP with zerocopy (xsk) functionality. The problem stems from an incorrect frame length validation during buffer processing, which could potentially allow for memory corruption or privilege escalation attacks. The vulnerability is classified under CWE-129 as an insufficient input validation, specifically related to improper bounds checking in network packet processing.
The technical flaw manifests in the buf_to_xdp function where the frame length check incorrectly accounts for virtio header size in all buffer cases. During XDP packet processing, the kernel allocates receive buffers with specific frame sizes and attempts to validate incoming packet lengths against these allocations. The current implementation uses xsk_pool_get_rx_frame_size() + vi->hdr_len for validation, treating all buffers uniformly regardless of their position in the receive chain. However, the first buffer in the XDP receive path includes the virtio header within its allocated space, while subsequent buffers do not. This discrepancy creates a scenario where a maliciously crafted packet could exceed the actual buffer capacity, potentially leading to buffer overflows or memory corruption.
The operational impact of this vulnerability is significant within virtualized network environments that utilize virtio-net devices with XDP support. Systems running Linux kernels with affected versions could experience instability, data corruption, or potential privilege escalation when processing network packets through XDP-enabled virtio networks. The vulnerability affects virtual machines and containers that rely on high-performance network processing through the XDP framework, particularly those using vhost-net implementations. Attackers could exploit this by crafting specific network packets that trigger the incorrect length validation, potentially leading to denial of service conditions or unauthorized access to kernel memory space.
Mitigation strategies should focus on applying the kernel patch that introduces an additional argument to buf_to_xdp to properly differentiate between first and subsequent buffers during frame length validation. System administrators should prioritize updating to patched kernel versions and ensure that virtualization environments using virtio-net with XDP are updated accordingly. Organizations should also implement network monitoring to detect unusual packet patterns that might indicate exploitation attempts. The fix aligns with ATT&CK technique T1059.003 for privilege escalation and T1499.004 for network denial of service, making it critical for security operations centers to monitor and remediate this vulnerability across their infrastructure. Regular kernel updates and security assessments should include verification of XDP-enabled network configurations to prevent exploitation of this class of vulnerability.