CVE-2026-74665
Received Received - Intake

Buffer Overflow in Linux Kernel XDP Processing

Publication date: 2026-08-22

Last updated on: 2026-08-22

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: net: fix skb length accounting after generic XDP frag adjustment Generic XDP exposes non-linear skb fragments through an xdp_buff. If an XDP program adjusts the fragment area, bpf_prog_run_generic_xdp() copies xdp_frags_size back to skb->data_len but leaves skb->len containing the old fragment contribution. After a fragment shrink, this makes skb_headlen() larger than the actual linear area. In the reproduced UDP receive path, __skb_datagram_iter() copied 1024 bytes past the actual linear tail to userspace, starting at struct skb_shared_info. The copied bytes included the affected skb's nr_frags, xdp_frags_size and a kernel pointer from skb_shinfo(skb)->frags[0]. Real packet data was displaced by the same amount and truncated at the end. Subtract the old data_len before replacing it and add the new data_len afterwards, keeping skb->len and skb->data_len synchronized. A 60000-byte UDP datagram on a veth pair with MTU 64000 was shortened by 1024 bytes from its fragment area. Before the fix, all 10 runs produced corrupted payloads. After the fix, all 10 runs matched the expected payload exactly.

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Meta Information

Published
2026-08-22
Last Modified
2026-08-22
Generated
2026-08-22
AI Q&A
2026-08-22
EPSS Evaluated
N/A
NVD
CVE-2026-74665
EUVD
EUVD-2026-64352

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *

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Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability in the Linux kernel involves incorrect accounting of skb (socket buffer) fragment sizes when Generic XDP (eXpress Data Path) programs adjust the fragment area. After a fragment shrink, the kernel's skb_headlen() reports a larger linear area than actually exists, causing data corruption during packet processing. Specifically, it can copy 1024 extra bytes past the linear tail, including sensitive kernel memory like skb_shared_info and frags data.

Detection Guidance

This vulnerability is specific to the Linux kernel's XDP (eXpress Data Path) implementation and may not have direct detection commands. Monitor kernel logs for XDP-related errors or corruption in network packet handling. Check for mismatches between skb->len and skb->data_len in kernel traces.

Impact Analysis

This vulnerability can lead to data corruption in network packets, potentially exposing sensitive kernel memory to userspace applications. In the worst case, it may cause applications to receive truncated or incorrect data, leading to crashes or security issues. Systems using Generic XDP with UDP traffic are particularly affected.

Mitigation Strategies

Apply the latest Linux kernel patches that address this issue. Update to a kernel version containing the fix for the XDP fragment adjustment vulnerability. Monitor network traffic for corruption or unexpected behavior after patching.

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