CVE-2025-40004
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.
Affected versions
Linux kernel versions
6.12
and later are affected. Fixed in
6.12.53,
6.17.3,
6.18
and their respective stable series.
References
The following references provide additional information about CVE-2025-40004 including vendor advisories, patch commits, exploit details, and third-party analysis. Links are sourced from the NIST NVD database.
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PatchKernel patch commithttps://git.kernel.org/stable/c/0da18d49f874d444ad83c8a546fa33bfcf2f582c
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PatchKernel patch commithttps://git.kernel.org/stable/c/c04db81cd0288dfc68b7a0f7d09bd49b40bba451
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PatchKernel patch commithttps://git.kernel.org/stable/c/df8462f0fc045b4475dc494a5787a03c972ba2a2
Frequently asked questions
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What is CVE-2025-40004?
CVE-2025-40004 is a unscored severity Linux kernel vulnerability . It affects Linux kernel versions from 6.12 onward and has been patched in 6.12.53, 6.17.3 and 6.18. CVE-2025-40004 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
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Is there a patch available for CVE-2025-40004?
Yes — CVE-2025-40004 has been patched. Fixed versions include 6.12.53, 6.17.3 and 6.18. If you are running Linux kernel 6.12 or later up to the fix versions, apply the relevant patch for your kernel branch.
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Is CVE-2025-40004 actively exploited?
No — CVE-2025-40004 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.