CVE-2026-63821

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

wifi: rtw88: usb: fix memory leaks on USB write failures

When rtw_usb_write_port() fails to submit a USB Request Block (URB)

(e.g., due to device disconnect or ENOMEM), the completion callback is

never executed.

Currently, the driver ignores the return value of rtw_usb_write_port()

in rtw_usb_write_data() and rtw_usb_tx_agg_skb(). Because these

functions rely on the completion callback to free the socket buffers

(skbs) and the transaction control block (txcb), a submission failure

results in:

1. A memory leak of the allocated skb in rtw_usb_write_data().

2. A memory leak of the txcb structure and all aggregated skbs in

rtw_usb_tx_agg_skb().

Fix this by checking the return value of rtw_usb_write_port(). If it

fails, explicitly free the skb in rtw_usb_write_data(), and properly

purge the tx_ack_queue and free the txcb in rtw_usb_tx_agg_skb().

The issue was discovered in practice during device disconnect/reconnect

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References