Linux hwe edge: In the Linux kernel, the following vulnerability has been resolved: usb: gadget: f_fs: Initialize epfile->in early to fix endpoint direction checks… (CVE-2026-64327)
A vulnerability in the Linux kernel's USB gadget function filesystem (functionfs) was fixed by initializing the epfile->in field earlier to ensure correct endpoint direction checks. Previously, epfile->in was only set upon USB host connection, causing early userspace ioctls to see incorrect DMA directions. This flaw could lead to incorrect DMA operations before the host connection. The issue affects Linux kernel versions prior to specific 7.0.0-xx releases for the linux-hwe-edge package. A patch is available and should be applied to mitigate the issue.
AI Analysis
Technical Summary
The vulnerability in the Linux kernel's USB gadget function filesystem (functionfs) involved improper initialization timing of the epfile->in field, which indicates endpoint direction. The field was only populated during USB host connection, but early userspace ioctls such as FUNCTIONFS_DMABUF_ATTACH that run before host connection would see epfile->in as zero, resulting in incorrect DMA direction handling. The fix moves the initialization to the creation of endpoint files, ensuring epfile->in is accurate before userspace opens endpoint files. This resolves potential incorrect DMA direction issues in early USB gadget operations.
Potential Impact
The vulnerability could cause incorrect DMA directions in early userspace USB gadget operations before the USB host connection is established. This may lead to improper DMA behavior, potentially affecting device communication or stability. The CVSS score is 5.5 (medium severity) with an impact primarily on availability (denial of service or disruption). No confidentiality or integrity impacts are indicated. No known exploits in the wild have been reported.
Mitigation Recommendations
A patch is available and should be applied by updating the Linux kernel to the fixed versions listed in the vendor advisory. After updating, a system reboot is required. Due to an ABI change, third-party kernel modules must be recompiled and reinstalled. Follow the vendor's update instructions carefully to ensure full remediation.
Linux hwe edge: In the Linux kernel, the following vulnerability has been resolved: usb: gadget: f_fs: Initialize epfile->in early to fix endpoint direction checks… (CVE-2026-64327)
Description
A vulnerability in the Linux kernel's USB gadget function filesystem (functionfs) was fixed by initializing the epfile->in field earlier to ensure correct endpoint direction checks. Previously, epfile->in was only set upon USB host connection, causing early userspace ioctls to see incorrect DMA directions. This flaw could lead to incorrect DMA operations before the host connection. The issue affects Linux kernel versions prior to specific 7.0.0-xx releases for the linux-hwe-edge package. A patch is available and should be applied to mitigate the issue.
CVSS v3.1
Score 5.5medium
Affected software
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability in the Linux kernel's USB gadget function filesystem (functionfs) involved improper initialization timing of the epfile->in field, which indicates endpoint direction. The field was only populated during USB host connection, but early userspace ioctls such as FUNCTIONFS_DMABUF_ATTACH that run before host connection would see epfile->in as zero, resulting in incorrect DMA direction handling. The fix moves the initialization to the creation of endpoint files, ensuring epfile->in is accurate before userspace opens endpoint files. This resolves potential incorrect DMA direction issues in early USB gadget operations.
Potential Impact
The vulnerability could cause incorrect DMA directions in early userspace USB gadget operations before the USB host connection is established. This may lead to improper DMA behavior, potentially affecting device communication or stability. The CVSS score is 5.5 (medium severity) with an impact primarily on availability (denial of service or disruption). No confidentiality or integrity impacts are indicated. No known exploits in the wild have been reported.
Mitigation Recommendations
A patch is available and should be applied by updating the Linux kernel to the fixed versions listed in the vendor advisory. After updating, a system reboot is required. Due to an ABI change, third-party kernel modules must be recompiled and reinstalled. Follow the vendor's update instructions carefully to ensure full remediation.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-gjhh-5f46-ffh6
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2026-64327"]
- Ecosystems
- []
- Database Specific Severity
- null
- Cvss Version
- null
Threat ID: 6a65420d9c2644c7f80859cf
Added to database: 07/25/2026, 23:09:01 UTC
Last enriched: 09/07/2026, 18:09:20 UTC
Last updated: 09/07/2026, 18:09:20 UTC
Views: 78
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