CVE-2026-64137

HIGHCVSS 7.8/10EPSS 0.13%

Last modified

CVE-2026-64137 is a high-severity vulnerability rated 7.8/10 on the CVSS scale. 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. EPSS estimates a 0.13% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1
7.8/10

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS Probability
0.13%

3.0th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
LinuxLinux>= fed979a7e082bd9f25f9002c3c4f8740dacd0bc8, < 9cf7eb8919344932f909b2fac76296f7656fda8d; >= fed979a7e082bd9f25f9002c3c4f8740dacd0bc8, < 9919021a3b7974ae66a5f9915e3a48c10cfd409b; >= fed979a7e082bd9f25f9002c3c4f8740dacd0bc8, < 969bc6370334a5b4720c5470783295d6484bbc95; >= fed979a7e082bd9f25f9002c3c4f8740dacd0bc8, < a3238b09c58f323e40743ce174cd0ab81b5c09ed; >= fed979a7e082bd9f25f9002c3c4f8740dacd0bc8, < a8d17d22db591099519a89f14dd24810daba74c3; >= fed979a7e082bd9f25f9002c3c4f8740dacd0bc8, < c2397b93fbb6f44a788fff30f99be2c20cc5e50f; >= fed979a7e082bd9f25f9002c3c4f8740dacd0bc8, < d1ebfce2c1d161186a82e77590bf7da2ea1bce91
LinuxLinux5.11

References

Timeline

Published
Last Modified
Status
Awaiting Analysis

Frequently Asked Questions

What is CVE-2026-64137?
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.
How severe is CVE-2026-64137?
CVE-2026-64137 has a CVSS score of 7.8/10 (HIGH severity). The EPSS model estimates a 0.13% probability of exploitation in the next 30 days.
How do I fix CVE-2026-64137?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST