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

mediumCVSS 5.5CVE-2026-63821

CSIRTS triage

vendor: KVM product: KVMOther

What: The vulnerability fixes memory leaks on USB write failures in the rtw88 driver.
Who is affected: Deployments of KVM that use the rtw88 USB Wi-Fi driver.
Urgency: Remediation is necessary to prevent resource exhaustion.
Action: Update to the latest version of KVM.

AI-assisted analysis generated from the source advisory — verify against the original.

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Details

Source: Microsoft Security Response Center (INTL · vendor-psirt · site)
Severity: medium — CVSS 5.5
Published: 2026-07-14
Exploitation: Not in CISA KEV at last sync

Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-63821

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Low exploitation riskCVE-2026-638210.16% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 5% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-63821	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

unknownCVE-2026-63821: In the Linux kernel, the following vulnerability has been resolved: wifi: rtw88: usb: fix memo…nvd

Recent advisories for wifi

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

mediumCVE-2026-67596: CSL 1010 M2M 3G WiFi Module firmware through 2.2.1.4 contains a weak encryption vulnerability …nvd · 2026-07-30
highCVE-2026-64515: In the Linux kernel, the following vulnerability has been resolved: wifi: mac80211: fix MLE de…nvd · 2026-07-25
unknownCVE-2026-64506: In the Linux kernel, the following vulnerability has been resolved: wifi: rtw89: correct drop …nvd · 2026-07-25
unknownCVE-2026-64325: In the Linux kernel, the following vulnerability has been resolved: wifi: mt76: mt7921/mt7925:…nvd · 2026-07-25
highCVE-2026-64255: In the Linux kernel, the following vulnerability has been resolved: wifi: iwlwifi: mld: valida…nvd · 2026-07-24
highCVE-2026-64223: In the Linux kernel, the following vulnerability has been resolved: wifi: mac80211: consume on…nvd · 2026-07-24