CVE-2026-74679
Received Received - Intake

Integer Overflow in Linux Kernel USB Gadget NCM Driver

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: usb: gadget: f_ncm: Use unsigned int for ndp_index The variable ndp_index is declared as a signed integer, but it stores the return value of get_ncm(), which is unsigned. A malicious host can supply a large offset that overflows the signed ndp_index, making it negative. Because ndp_index is compared against unsigned bounds, this negative value bypasses sanity checks and leads to an out-of-bounds read when calculating the address of the NDP block (ntb_ptr + ndp_index). Fix this by changing ndp_index to unsigned int to ensure consistent unsigned comparisons throughout the function.

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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-2026-74679
EUVD
EUVD-2026-64366

Affected Vendors & Products

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

Helpful Resources

Exploitability

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KEV
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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability is in the Linux kernel's USB gadget function f_ncm. It involves a signed integer variable ndp_index that should be unsigned. A malicious host can exploit this by providing a large offset that overflows ndp_index, making it negative. This bypasses sanity checks due to unsigned comparisons and leads to an out-of-bounds read when calculating the NDP block address.

Detection Guidance

This vulnerability is specific to the Linux kernel's USB gadget function f_ncm. Detection requires checking kernel versions and examining the source code for the signed ndp_index variable. No direct network commands detect this, but you can verify kernel versions and inspect kernel source code for the affected function.

Impact Analysis

This vulnerability could allow an attacker to read memory outside the intended bounds, potentially exposing sensitive data or causing system instability. If exploited, it may lead to unauthorized access or denial of service on systems using the affected Linux kernel component.

Mitigation Strategies

Apply the kernel patch that changes ndp_index from signed to unsigned int. Update to a kernel version containing the fix. If immediate patching is not possible, disable the USB gadget NCM function (CONFIG_USB_LIBCOMPOSITE) as a temporary workaround.

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