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VulnerabilityPublished

CVE-2026-63896: Linux kernel · usb: gadget: composite: fix integer underflow in WebUSB GET_URL handling

Affects Linux kernelSource GCVE Database

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Not known to be exploited.

Data as of 12 Nov 2026, 15:35 UTC

Severity
High

Rated High by Threat Radar's AI analysis · No CVSS score from NVD or the CNA

Thin evidence

One scorer or none

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 19 Jul 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq 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 12 Nov 2026.

What to do

AI-suggested

A fix for this vulnerability has been implemented in the Linux kernel by properly handling the case when the host-supplied wLength is smaller than the URL descriptor header length, preventing the integer underflow and out-of-bounds memory copy. Users and administrators should apply the official Linux kernel updates that include this fix. Since this is a kernel-level vulnerability, updating to a patched kernel version is the recommended remediation.

Description

A vulnerability in the Linux kernel's USB gadget composite driver related to the WebUSB GET_URL handler could cause an integer underflow. This flaw allows an unsigned subtraction to wrap when the host-supplied wLength is smaller than the URL descriptor header length, leading to an out-of-bounds memory copy. The issue is triggered by a USB host sending a crafted SETUP packet to any gadget with webusb/use=1 and a landingPage configured. The flaw has been fixed by properly handling cases where wLength is smaller than the header length to prevent excessive copying.

References

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