CVE-2026-64137: Linux kernel · smb: client: require net admin for CIFS SWN netlink
Source GCVE Database
Not known to be exploited · CVSS 7.8 High.
Data as of 26 Oct 2026, 14:05 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 2% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 19 Jul 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
AI-suggested
The vulnerability has been resolved by enforcing CAP_NET_ADMIN capability checks on relevant netlink operations and multicast group membership. The cifs.witness service runs with the necessary privileges to perform these actions. No further action is required if the system is updated with the fixed kernel version.
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.
References
- nvd.nist.gov/vuln/detail/CVE-2026-64137 (opens in a new tab)
- git.kernel.org/stable/c/969bc6370334a5b4720c5470783295d6484bbc95 (opens in a new tab)
- git.kernel.org/stable/c/9919021a3b7974ae66a5f9915e3a48c10cfd409b (opens in a new tab)
- git.kernel.org/stable/c/9cf7eb8919344932f909b2fac76296f7656fda8d (opens in a new tab)
- git.kernel.org/stable/c/a3238b09c58f323e40743ce174cd0ab81b5c09ed (opens in a new tab)
- git.kernel.org/stable/c/a8d17d22db591099519a89f14dd24810daba74c3 (opens in a new tab)
- git.kernel.org/stable/c/c2397b93fbb6f44a788fff30f99be2c20cc5e50f (opens in a new tab)
- git.kernel.org/stable/c/d1ebfce2c1d161186a82e77590bf7da2ea1bce91 (opens in a new tab)