In the Linux kernel, the following vulnerability has been resolved: smb: client: fix off-by-8 bounds check in check_wsl_eas() The bounds check uses…
A high-severity vulnerability in the Linux kernel SMB client was fixed involving an off-by-8 bounds check error in the check_wsl_eas() function. The flaw allowed an untrusted SMB server to leak up to 8 bytes of kernel heap memory during extended attribute (EA) name comparison, potentially influencing Windows Subsystem for Linux (WSL) extended attribute interpretation. The issue was due to incorrect pointer arithmetic in bounds checking, leading to out-of-bounds reads. This vulnerability affects multiple Linux kernel versions prior to specific patched releases. A patch is available and included in recent Linux kernel updates distributed by Ubuntu.
AI Analysis
Technical Summary
The vulnerability (CVE-2026-31614) in the Linux kernel SMB client arises from an off-by-8 error in the bounds check within the check_wsl_eas() function. The bounds check incorrectly calculates the end of the EA name and value by using (u8 *)ea + nlen + 1 + vlen, whereas the correct base should be ea->ea_data due to the offset of sizeof(struct smb2_file_full_ea_info) = 8 bytes. This miscalculation allows an untrusted SMB server to cause the kernel to read up to 8 bytes beyond the intended buffer, leaking kernel heap data during EA name comparison. The vulnerability impacts the interpretation of WSL extended attributes, potentially leaking sensitive kernel memory. The issue has been fixed by correcting the bounds check to use ea->ea_data as the base pointer. The fix is included in Linux kernel versions released after the affected versions listed.
Potential Impact
An untrusted SMB server can exploit this vulnerability to leak up to 8 bytes of kernel heap memory during the extended attribute name comparison process. This memory disclosure could influence how WSL extended attributes are interpreted, potentially leading to information leakage from kernel memory. The CVSS v3.1 score is 7.1 (high), reflecting local attack vector with low complexity and no user interaction required, resulting in high confidentiality impact and high availability impact but no integrity impact. There are no known exploits in the wild at this time.
Mitigation Recommendations
A patch is available and has been released by Ubuntu and other Linux distributions. Users should update their Linux kernel to the fixed versions listed in the vendor advisory and reboot their systems to apply the changes. Due to an ABI change in the kernel update, recompilation and reinstallation of third-party kernel modules may be required. Follow the vendor's update instructions carefully to ensure full remediation.
In the Linux kernel, the following vulnerability has been resolved: smb: client: fix off-by-8 bounds check in check_wsl_eas() The bounds check uses…
Description
A high-severity vulnerability in the Linux kernel SMB client was fixed involving an off-by-8 bounds check error in the check_wsl_eas() function. The flaw allowed an untrusted SMB server to leak up to 8 bytes of kernel heap memory during extended attribute (EA) name comparison, potentially influencing Windows Subsystem for Linux (WSL) extended attribute interpretation. The issue was due to incorrect pointer arithmetic in bounds checking, leading to out-of-bounds reads. This vulnerability affects multiple Linux kernel versions prior to specific patched releases. A patch is available and included in recent Linux kernel updates distributed by Ubuntu.
CVSS v3.1
Score 7.1high
Affected software
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protected]?arch=source&distro=resolutepkg:deb/ubuntu/[email protected]?arch=source&distro=resolutepkg:deb/ubuntu/[email protected]?arch=source&distro=resolutepkg:deb/ubuntu/[email protected]?arch=source&distro=resoluteRun on your own infrastructure? 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AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability (CVE-2026-31614) in the Linux kernel SMB client arises from an off-by-8 error in the bounds check within the check_wsl_eas() function. The bounds check incorrectly calculates the end of the EA name and value by using (u8 *)ea + nlen + 1 + vlen, whereas the correct base should be ea->ea_data due to the offset of sizeof(struct smb2_file_full_ea_info) = 8 bytes. This miscalculation allows an untrusted SMB server to cause the kernel to read up to 8 bytes beyond the intended buffer, leaking kernel heap data during EA name comparison. The vulnerability impacts the interpretation of WSL extended attributes, potentially leaking sensitive kernel memory. The issue has been fixed by correcting the bounds check to use ea->ea_data as the base pointer. The fix is included in Linux kernel versions released after the affected versions listed.
Potential Impact
An untrusted SMB server can exploit this vulnerability to leak up to 8 bytes of kernel heap memory during the extended attribute name comparison process. This memory disclosure could influence how WSL extended attributes are interpreted, potentially leading to information leakage from kernel memory. The CVSS v3.1 score is 7.1 (high), reflecting local attack vector with low complexity and no user interaction required, resulting in high confidentiality impact and high availability impact but no integrity impact. There are no known exploits in the wild at this time.
Mitigation Recommendations
A patch is available and has been released by Ubuntu and other Linux distributions. Users should update their Linux kernel to the fixed versions listed in the vendor advisory and reboot their systems to apply the changes. Due to an ABI change in the kernel update, recompilation and reinstallation of third-party kernel modules may be required. Follow the vendor's update instructions carefully to ensure full remediation.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- UBUNTU-CVE-2026-31614
- Osv Schema Version
- 1.7.0
- Ecosystems
- ["Ubuntu:Pro:14.04:LTS","Ubuntu:Pro:16.04:LTS","Ubuntu:16.04:LTS","Ubuntu:Pro:FIPS:16.04:LTS","Ubuntu:Pro:18.04:LTS","Ubuntu:18.04:LTS","Ubuntu:Pro:FIPS-updates:18.04:LTS","Ubuntu:Pro:FIPS:18.04:LTS","Ubuntu:Pro:20.04:LTS","Ubuntu:20.04:LTS","Ubuntu:Pro:FIPS-updates:20.04:LTS","Ubuntu:Pro:FIPS:20.04:LTS","Ubuntu:22.04:LTS","Ubuntu:Nvidia-BlueField:22.04:LTS","Ubuntu:Pro:FIPS-preview:22.04:LTS","Ubuntu:Pro:FIPS-updates:22.04:LTS","Ubuntu:Pro:Realtime:22.04:LTS","Ubuntu:24.04:LTS","Ubuntu:Nvidia-BlueField:24.04:LTS","Ubuntu:Pro:FIPS-updates:24.04:LTS","Ubuntu:Pro:Realtime:24.04:LTS","Ubuntu:25.10","Ubuntu:26.04:LTS"]
- Cvss Version
- 3.1
Threat ID: 6a5b61d82d1edb114c886515
Added to database: 07/18/2026, 11:22:00 UTC
Last enriched: 08/19/2026, 09:25:00 UTC
Last updated: 09/14/2026, 22:01:33 UTC
Views: 19
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