CVE-2026-63821: Linux kernel · wifi: rtw88: usb: fix memory leaks on USB write failures
Affects Linux kernelSource GCVE Database
Not known to be exploited · fixed in 7.0.0-31.31~24.04.1 : update Linux kernel when convenient.
Data as of 26 Oct 2026, 14:05 UTC
Rated by Threat Radar · No CVSS score from NVD or the CNA
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 5% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 7.0.0-31.31~24.04.1, 7.0.0-31.31, 7.0.0-1012.12 +7
Exploitation evidence
Disclosed: evidence found.
CVE published 19 Jul 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.04 LTSlinuxpkg:deb/ubuntu/linux?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-gkepkg:deb/ubuntu/linux-gke?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
A patch is available that fixes the memory leak by properly handling failures in USB write operations in the rtw88 driver. Users should update their Linux kernel to a fixed version as provided by their distribution vendor. No additional mitigation is required beyond applying the official fix.
Description
A memory leak vulnerability was fixed in the Linux kernel's rtw88 USB WiFi driver. The issue occurs when the rtw_usb_write_port() function fails to submit a USB Request Block (URB), causing the completion callback not to execute and resulting in memory leaks of socket buffers and transaction control blocks. This was observed during device disconnect/reconnect and memory pressure conditions. The fix involves checking the return value of rtw_usb_write_port() and explicitly freeing allocated memory on failure.
References
- ubuntu.com/security/CVE-2026-63821 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-63821 (opens in a new tab)
- git.kernel.org/linus/6b964941bbfe6e0f18b1a5e008486dbb62df440a (opens in a new tab)
- msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-63821.json (opens in a new tab)
- support.microsoft.com/lifecycle (opens in a new tab)
- first.org/cvss (opens in a new tab)
- ubuntu.com/security/notices/USN-8726-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8727-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8728-1 (opens in a new tab)