CVE-2026-64137

smb: client: require net admin for CIFS SWN netlink

State: Published
Severity: 7.8 High
Published: Jul 19, 2026
Updated: Aug 5, 2026
Reserved: Jul 19, 2026

Description

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.

Scores

CVSS	Score	Vector	Source
3.1	7.8 High	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H	Linux

Weaknesses

The record names no weakness.

Affected Products

Product	Versions
LinuxLinux	fed979a7e082bd9f25f9002c3c4f8740dacd0bc8 to before 9cf7eb8919344932f909b2fac76296f7656fda8dAffected fed979a7e082bd9f25f9002c3c4f8740dacd0bc8 to before 9919021a3b7974ae66a5f9915e3a48c10cfd409bAffected fed979a7e082bd9f25f9002c3c4f8740dacd0bc8 to before 969bc6370334a5b4720c5470783295d6484bbc95Affected fed979a7e082bd9f25f9002c3c4f8740dacd0bc8 to before a3238b09c58f323e40743ce174cd0ab81b5c09edAffected fed979a7e082bd9f25f9002c3c4f8740dacd0bc8 to before a8d17d22db591099519a89f14dd24810daba74c3Affected fed979a7e082bd9f25f9002c3c4f8740dacd0bc8 to before c2397b93fbb6f44a788fff30f99be2c20cc5e50fAffected fed979a7e082bd9f25f9002c3c4f8740dacd0bc8 to before d1ebfce2c1d161186a82e77590bf7da2ea1bce91Affected
LinuxLinux	5.11Affected before 5.11Not affected 5.15.210 through 5.15.Not affected 6.1.176 through 6.1.Not affected 6.6.143 through 6.6.Not affected 6.12.92 through 6.12.Not affected 6.18.34 through 6.18.Not affected 7.0.11 through 7.0.Not affected 7.1 and laterNot affected

Product

Versions

LinuxLinux

fed979a7e082bd9f25f9002c3c4f8740dacd0bc8 to before 9cf7eb8919344932f909b2fac76296f7656fda8dAffected
fed979a7e082bd9f25f9002c3c4f8740dacd0bc8 to before 9919021a3b7974ae66a5f9915e3a48c10cfd409bAffected
fed979a7e082bd9f25f9002c3c4f8740dacd0bc8 to before 969bc6370334a5b4720c5470783295d6484bbc95Affected
fed979a7e082bd9f25f9002c3c4f8740dacd0bc8 to before a3238b09c58f323e40743ce174cd0ab81b5c09edAffected
fed979a7e082bd9f25f9002c3c4f8740dacd0bc8 to before a8d17d22db591099519a89f14dd24810daba74c3Affected
fed979a7e082bd9f25f9002c3c4f8740dacd0bc8 to before c2397b93fbb6f44a788fff30f99be2c20cc5e50fAffected
fed979a7e082bd9f25f9002c3c4f8740dacd0bc8 to before d1ebfce2c1d161186a82e77590bf7da2ea1bce91Affected

LinuxLinux

5.11Affected
before 5.11Not affected
5.15.210 through 5.15.*Not affected
6.1.176 through 6.1.*Not affected
6.6.143 through 6.6.*Not affected
6.12.92 through 6.12.*Not affected
6.18.34 through 6.18.*Not affected
7.0.11 through 7.0.*Not affected
7.1 and laterNot affected

References

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