CVE-2026-64137 is a vulnerability in Linux Kernel
Published on July 19, 2026
smb: client: require net admin for CIFS SWN netlink
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.
Products Associated with CVE-2026-64137
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Affected Versions
Linux:- Version fed979a7e082bd9f25f9002c3c4f8740dacd0bc8 and below 9cf7eb8919344932f909b2fac76296f7656fda8d is affected.
- Version fed979a7e082bd9f25f9002c3c4f8740dacd0bc8 and below 9919021a3b7974ae66a5f9915e3a48c10cfd409b is affected.
- Version fed979a7e082bd9f25f9002c3c4f8740dacd0bc8 and below 969bc6370334a5b4720c5470783295d6484bbc95 is affected.
- Version fed979a7e082bd9f25f9002c3c4f8740dacd0bc8 and below a3238b09c58f323e40743ce174cd0ab81b5c09ed is affected.
- Version fed979a7e082bd9f25f9002c3c4f8740dacd0bc8 and below a8d17d22db591099519a89f14dd24810daba74c3 is affected.
- Version fed979a7e082bd9f25f9002c3c4f8740dacd0bc8 and below c2397b93fbb6f44a788fff30f99be2c20cc5e50f is affected.
- Version fed979a7e082bd9f25f9002c3c4f8740dacd0bc8 and below d1ebfce2c1d161186a82e77590bf7da2ea1bce91 is affected.
- Version 5.11 is affected.
- Before 5.11 is unaffected.
- Version 5.15.210, <= 5.15.* is unaffected.
- Version 6.1.176, <= 6.1.* is unaffected.
- Version 6.6.143, <= 6.6.* is unaffected.
- Version 6.12.92, <= 6.12.* is unaffected.
- Version 6.18.34, <= 6.18.* is unaffected.
- Version 7.0.11, <= 7.0.* is unaffected.
- Version 7.1, <= * is unaffected.