CVE-2026-64137 (GCVE-0-2026-64137)

Vulnerability from cvelistv5 – Published: 2026-07-19 15:40 – Updated: 2026-07-20 13:43
VLAI
Title
smb: client: require net admin for CIFS SWN netlink
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.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: fed979a7e082bd9f25f9002c3c4f8740dacd0bc8 , < 9cf7eb8919344932f909b2fac76296f7656fda8d (git)
Affected: fed979a7e082bd9f25f9002c3c4f8740dacd0bc8 , < 9919021a3b7974ae66a5f9915e3a48c10cfd409b (git)
Affected: fed979a7e082bd9f25f9002c3c4f8740dacd0bc8 , < 969bc6370334a5b4720c5470783295d6484bbc95 (git)
Affected: fed979a7e082bd9f25f9002c3c4f8740dacd0bc8 , < a3238b09c58f323e40743ce174cd0ab81b5c09ed (git)
Affected: fed979a7e082bd9f25f9002c3c4f8740dacd0bc8 , < a8d17d22db591099519a89f14dd24810daba74c3 (git)
Affected: fed979a7e082bd9f25f9002c3c4f8740dacd0bc8 , < c2397b93fbb6f44a788fff30f99be2c20cc5e50f (git)
Affected: fed979a7e082bd9f25f9002c3c4f8740dacd0bc8 , < d1ebfce2c1d161186a82e77590bf7da2ea1bce91 (git)
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Linux Linux Affected: 5.11
Unaffected: 0 , < 5.11 (semver)
Unaffected: 5.15.210 , ≤ 5.15.* (semver)
Unaffected: 6.1.176 , ≤ 6.1.* (semver)
Unaffected: 6.6.143 , ≤ 6.6.* (semver)
Unaffected: 6.12.92 , ≤ 6.12.* (semver)
Unaffected: 6.18.34 , ≤ 6.18.* (semver)
Unaffected: 7.0.11 , ≤ 7.0.* (semver)
Unaffected: 7.1 , ≤ * (original_commit_for_fix)
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{
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Register messages sent to that group include the witness\\nregistration id and, for NTLM-authenticated mounts, the username, domain,\\nand password attributes copied from the CIFS session.  An unprivileged\\nlocal process should not be able to join that group and receive those\\nmessages.\\n\\nRequire CAP_NET_ADMIN for incoming SWN_NOTIFY commands with\\nGENL_ADMIN_PERM, and require CAP_NET_ADMIN over the network namespace for\\njoining the SWN multicast group with GENL_MCAST_CAP_NET_ADMIN.  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    "redhat_vex": {
      "aggregate_severity": "Important",
      "current_release_date": "2026-07-20T15:25:59+00:00",
      "cve": "CVE-2026-64137",
      "id": "CVE-2026-64137",
      "initial_release_date": "2026-07-19T00:00:00+00:00",
      "product_status:known_not_affected": "274",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: smb: client: require net admin for CIFS SWN netlink",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-64137.json",
      "version": "3"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.