CVE-2026-31614 smb: client: fix off-by-8 bounds check in check_wsl_eas()

High 7.1 Published 24 Apr 2026 Updated 14 Jun 2026

A malicious SMB server can trigger an off-by-8 bounds check error in the Linux kernel SMB client, leaking up to 8 bytes of kernel heap memory.

Exploited in the wild: Not known
Login needed: Any signed-in user
Attackable: Local or same network only
Victim action needed: Not needed
Fix: Available

What is CVE-2026-31614?

CVE-2026-31614 is a high-severity vulnerability in Linux kernel, published on 24 Apr 2026. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

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 (u8 *)ea + nlen + 1 + vlen as the end of the EA name and value, but ea_data sits at offset sizeof(struct smb2_file_full_ea_info) = 8 from ea, not at offset 0. The strncmp() later reads ea->ea_data[0..nlen-1] and the value bytes follow at ea_data[nlen+1..nlen+vlen], so the actual end is ea->ea_data + nlen + 1 + vlen. Isn't pointer math fun?

The earlier check (u8 *)ea > end - sizeof(*ea) only guarantees the 8-byte header is in bounds, but since the last EA is placed within 8 bytes of the end of the response, the name and value bytes are read past the end of iov.

Fix this mess all up by using ea->ea_data as the base for the bounds check.

An "untrusted" server can use this to leak up to 8 bytes of kernel heap into the EA name comparison and influence which WSL xattr the data is interpreted as.

Weakness: CWE-125

Which versions are affected by CVE-2026-31614?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2026-31614?

Apply the vendor's patch.

Is CVE-2026-31614 being exploited?

There is no known exploitation of CVE-2026-31614 in the wild and no public exploit code.

All Linux kernel vulnerabilities

Sources

Also known as AZL-83852, BELL-CVE-2026-31614, DEBIAN-CVE-2026-31614, GHSA-p37w-xhv5-6c8j, ROOT-OS-DEBIAN-13-CVE-2026-31614, ROOT-OS-UBUNTU-2204-CVE-2026-31614 and 2 more.