CVE-2025-40004net/9p: Fix buffer overflow in USB transport layer

In the Linux kernel, the following vulnerability has been resolved: net/9p: Fix buffer overflow in USB transport layer A buffer overflow vulnerability exists in the USB 9pfs transport layer where inconsistent size validation between packet header parsing and actual data copying allows a malicious USB host to overflow heap buffers. The issue occurs because: - usb9pfs_rx_header() validates only the declared size in packet header - usb9pfs_rx_complete() uses req->actual (actual received bytes) for memcpy This allows an attacker to craft packets with small declared size (bypassing validation) but large actual payload (triggering overflow in memcpy). Add validation in usb9pfs_rx_complete() to ensure req->actual does not exceed the buffer capacity before copying data.

CVSS

Not yet scored

Weakness (CWE)

Not given

Known exploited

Not in CISA's KEV catalog

EPSS (exploitation in the next 30 days)

Not loaded for this CVE

Assigned by

Linux

NVD analysis

Deferred

Record last updated

May 11, 2026

First seen by InfoSec Signals

Oct 9, 2026

The CVE record on cve.org · NVD's entry

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