CVE-2026-74678
Received Received - Intake

Memory Leak in Linux Kernel USB Network 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: net: usb: ax88179_178a: fix skb leak in ax88179_tx_fixup() When the interface has NETIF_F_SG enabled and skb_linearize() fails in ax88179_tx_fixup(), the function returns NULL without freeing the skb. usbnet_start_xmit() treats a NULL return from tx_fixup() as a drop (info->flags does not set FLAG_MULTI_PACKET for this driver), jumping to the "drop" label where it does `if (skb) dev_kfree_skb_any(skb)`. Because tx_fixup() returned NULL, the local skb variable in usbnet_start_xmit() is NULL, so the original skb is never freed — a memory leak on every TX frame whose linearization fails (i.e. under memory pressure). Free the skb before returning, matching the error handling already used for the pskb_expand_head() failure path in the same 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-2026-74678
EUVD
EUVD-2026-64365

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 is a memory leak vulnerability in the Linux kernel's USB network driver ax88179_178a. When the network interface has scatter/gather I/O enabled and skb_linearize() fails during packet transmission, the driver's tx_fixup function returns NULL without freeing the socket buffer (skb). This causes the original skb to never be freed, resulting in a memory leak on every failed transmission.

Detection Guidance

This vulnerability is specific to the Linux kernel's USB network driver (ax88179_178a) and may not have direct detection commands. Monitor kernel logs for skb-related errors or memory leaks during USB network operations. Check for increased memory usage on systems using the ax88179 driver.

Impact Analysis

This vulnerability can cause system memory exhaustion over time due to unreleased network buffers. It may lead to degraded network performance, application crashes, or system instability, particularly under memory pressure conditions when linearization fails frequently.

Mitigation Strategies

Apply the latest Linux kernel updates to patch this issue. Disable NETIF_F_SG feature for the ax88179 driver if possible. Monitor network interfaces for abnormal behavior or memory leaks. Restrict untrusted USB network devices.

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