PT-2026-61454 · Linux · Linux

CVE-2026-64137 · Published 2026-07-19 · Updated 2026-07-19

NVD

CVSS v3.1

7.8

High

Base vector

AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

In the Linux kernel, the following vulnerability has been resolved:

smb: client: require net admin for CIFS SWN netlink

CIFS GENL CMD SWN NOTIFY is the userspace witness-notify command. The intended sender is the cifs.witness helper, but the generic-netlink operation currently has no capability flag, so any local process can send RESOURCE CHANGE or CLIENT MOVE notifications to the in-kernel witness handler.

The same family exposes CIFS GENL MCGRP SWN without multicast-group capability flags. Register messages sent to that group include the witness registration id and, for NTLM-authenticated mounts, the username, domain, and password attributes copied from the CIFS session. An unprivileged local process should not be able to join that group and receive those messages.

Require CAP NET ADMIN for incoming SWN NOTIFY commands with GENL ADMIN PERM, and require CAP NET ADMIN over the network namespace for joining the SWN multicast group with GENL MCAST CAP NET ADMIN. The cifs.witness service runs with the privileges needed for both operations.

Fix

Related Identifiers

CVE-2026-64137

Affected Products

Linux

References · 8

• https://nvd.nist.gov/vuln/detail/CVE-2026-64137 · Security Note
• https://git.kernel.org/stable/c/969bc6370334a5b4720c5470783295d6484bbc95 · Note
• https://git.kernel.org/stable/c/a3238b09c58f323e40743ce174cd0ab81b5c09ed · Note
• https://git.kernel.org/stable/c/9919021a3b7974ae66a5f9915e3a48c10cfd409b · Note
• https://git.kernel.org/stable/c/c2397b93fbb6f44a788fff30f99be2c20cc5e50f · Note
• https://git.kernel.org/stable/c/a8d17d22db591099519a89f14dd24810daba74c3 · Note
• https://git.kernel.org/stable/c/d1ebfce2c1d161186a82e77590bf7da2ea1bce91 · Note
• https://git.kernel.org/stable/c/9cf7eb8919344932f909b2fac76296f7656fda8d · Note