CVE-2026-63821
wifi: rtw88: usb: fix memory leaks on USB write failures
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.
INFO
Published Date :
July 19, 2026, 12:16 p.m.
Last Modified :
July 19, 2026, 12:16 p.m.
Remotely Exploit :
No
Source :
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Affected Products
The following products are affected by CVE-2026-63821
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
Solution
- Check return value of rtw_usb_write_port().
- Free skb on submission failure.
- Purge tx_ack_queue on failure.
- Free txcb structure on failure.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-63821.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-63821 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-63821
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-63821 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-63821 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Jul. 19, 2026
Action Type Old Value New Value Added Affected [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': 'a82dfd33d1237f6c0fb8a7077022189d1fc7ec98', 'lessThan': '2b2060c2075a72bc2de43ce5e1b9347d6c5e27bb', 'versionType': 'git'}, {'status': 'affected', 'version': 'a82dfd33d1237f6c0fb8a7077022189d1fc7ec98', 'lessThan': '53fed4061a09755de99c89fdc7fae5b794da455f', 'versionType': 'git'}, {'status': 'affected', 'version': 'a82dfd33d1237f6c0fb8a7077022189d1fc7ec98', 'lessThan': '200d58c851b8f63f77a05570072dd20f79bc3681', 'versionType': 'git'}, {'status': 'affected', 'version': 'a82dfd33d1237f6c0fb8a7077022189d1fc7ec98', 'lessThan': '8206d173d18ef5a077423119f4e9a93cb3a6f4eb', 'versionType': 'git'}, {'status': 'affected', 'version': 'a82dfd33d1237f6c0fb8a7077022189d1fc7ec98', 'lessThan': '6b964941bbfe6e0f18b1a5e008486dbb62df440a', 'versionType': 'git'}], 'programFiles': ['drivers/net/wireless/realtek/rtw88/usb.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '6.2'}, {'status': 'unaffected', 'version': '0', 'lessThan': '6.2', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '6.6.144', 'versionType': 'semver', 'lessThanOrEqual': '6.6.*'}, {'status': 'unaffected', 'version': '6.12.95', 'versionType': 'semver', 'lessThanOrEqual': '6.12.*'}, {'status': 'unaffected', 'version': '6.18.38', 'versionType': 'semver', 'lessThanOrEqual': '6.18.*'}, {'status': 'unaffected', 'version': '7.1.3', 'versionType': 'semver', 'lessThanOrEqual': '7.1.*'}, {'status': 'unaffected', 'version': '7.2-rc1', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['drivers/net/wireless/realtek/rtw88/usb.c'], 'defaultStatus': 'affected'}] Added 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. Added Reference https://git.kernel.org/stable/c/200d58c851b8f63f77a05570072dd20f79bc3681 Added Reference https://git.kernel.org/stable/c/2b2060c2075a72bc2de43ce5e1b9347d6c5e27bb Added Reference https://git.kernel.org/stable/c/53fed4061a09755de99c89fdc7fae5b794da455f Added Reference https://git.kernel.org/stable/c/6b964941bbfe6e0f18b1a5e008486dbb62df440a Added Reference https://git.kernel.org/stable/c/8206d173d18ef5a077423119f4e9a93cb3a6f4eb