Use-after-free in Linux kernel - CVE-2026-63894
Published: July 20, 2026
Vulnerability identifier: #VU138761
CSH Severity: Low
CVSS v4.0: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear
CVE-ID: CVE-2026-63894
CWE-ID: CWE-416
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vendor: Linux Foundation
Affected software:
Linux kernel
Linux kernel
Detailed vulnerability description
The vulnerability allows a local privileged user to cause a denial of service.
The vulnerability exists due to a use-after-free in the FunctionFS DMABUF cancel and release paths when handling a concurrent request completion and detach or close operation. A local privileged user can trigger a DMABUF detach ioctl or close the FunctionFS device during request completion to cause a denial of service.
The issue is reachable from the FunctionFS device node and is not reachable from an attached USB host on the cable. Deployments may delegate the device node to a non-root gadget service.
How to mitigate CVE-2026-63894
Install security update from vendor's repository.