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Advisory severityHigh7.0Red Hat Linux

High [CVE-2026-64137] require net admin for CIFS SWN netlink

This high-severity Red Hat Linux advisory covers CVE-2026-64137.

Aggregated and source-linked by VulniPulse. Data sources, validation and limitations.

CVE-2026-64137 Source published Source updated

VulniPulse record published Record updated

CVE-2026-64137
Affected products & platforms
Red Hat LinuxUnclassified
Open source advisory

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Summary

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.

A flaw was found in the Linux kernel's Common Internet File System (CIFS) client. This vulnerability allows an unprivileged local user to send witness notifications or join a specific multicast group without proper administrative privileges.

Affected versions

No affected-version range was extracted from the source record. The vendor advisory is authoritative. Check it before change work.

Official advisory · high-confidence parse· fetched 6 days ago·verify at source

Fixed versions

No fixed release is recorded yet. That does not prove no patch exists. Confirm against the vendor advisory.

Official advisory · high-confidence parse· fetched 6 days ago·verify at source

Mitigation checklist

Recommended fix / mitigation
  • Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.

Official advisory · high-confidence parse· fetched 6 days ago·verify at source

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