{"id":"CVE-2026-64137","state":"PUBLISHED","title":"smb: client: require net admin for CIFS SWN netlink","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: require net admin for CIFS SWN netlink\n\nCIFS_GENL_CMD_SWN_NOTIFY is the userspace witness-notify command.  The\nintended sender is the cifs.witness helper, but the generic-netlink\noperation currently has no capability flag, so any local process can send\nRESOURCE_CHANGE or CLIENT_MOVE notifications to the in-kernel witness\nhandler.\n\nThe same family exposes CIFS_GENL_MCGRP_SWN without multicast-group\ncapability flags.  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.  The\ncifs.witness service runs with the privileges needed for both operations.","publishedAt":"2026-07-19T15:40:31.045Z","updatedAt":"2026-08-05T12:39:38.366Z","severity":{"score":7.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"fed979a7e082bd9f25f9002c3c4f8740dacd0bc8","status":"affected","lessThan":"9cf7eb8919344932f909b2fac76296f7656fda8d","versionType":"git"},{"version":"fed979a7e082bd9f25f9002c3c4f8740dacd0bc8","status":"affected","lessThan":"9919021a3b7974ae66a5f9915e3a48c10cfd409b","versionType":"git"},{"version":"fed979a7e082bd9f25f9002c3c4f8740dacd0bc8","status":"affected","lessThan":"969bc6370334a5b4720c5470783295d6484bbc95","versionType":"git"},{"version":"fed979a7e082bd9f25f9002c3c4f8740dacd0bc8","status":"affected","lessThan":"a3238b09c58f323e40743ce174cd0ab81b5c09ed","versionType":"git"},{"version":"fed979a7e082bd9f25f9002c3c4f8740dacd0bc8","status":"affected","lessThan":"a8d17d22db591099519a89f14dd24810daba74c3","versionType":"git"},{"version":"fed979a7e082bd9f25f9002c3c4f8740dacd0bc8","status":"affected","lessThan":"c2397b93fbb6f44a788fff30f99be2c20cc5e50f","versionType":"git"},{"version":"fed979a7e082bd9f25f9002c3c4f8740dacd0bc8","status":"affected","lessThan":"d1ebfce2c1d161186a82e77590bf7da2ea1bce91","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/smb/client/netlink.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.11","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.11","versionType":"semver"},{"version":"5.15.210","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.176","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.143","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.92","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.34","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.11","status":"unaffected","lessThanOrEqual":"7.0.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/smb/client/netlink.c"]}],"references":["https://git.kernel.org/stable/c/9cf7eb8919344932f909b2fac76296f7656fda8d","https://git.kernel.org/stable/c/9919021a3b7974ae66a5f9915e3a48c10cfd409b","https://git.kernel.org/stable/c/969bc6370334a5b4720c5470783295d6484bbc95","https://git.kernel.org/stable/c/a3238b09c58f323e40743ce174cd0ab81b5c09ed","https://git.kernel.org/stable/c/a8d17d22db591099519a89f14dd24810daba74c3","https://git.kernel.org/stable/c/c2397b93fbb6f44a788fff30f99be2c20cc5e50f","https://git.kernel.org/stable/c/d1ebfce2c1d161186a82e77590bf7da2ea1bce91"],"weaknesses":[],"ingestedAt":"2026-10-29T20:12:41.951Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/64xxx/CVE-2026-64137.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-64137","state":"PUBLISHED","datePublished":"2026-07-19T15:40:31.045Z","dateUpdated":"2026-08-05T12:39:38.366Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-07-19T07:54:57.037Z"},"containers":{"cna":{"title":"smb: client: require net admin for CIFS SWN netlink","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: require net admin for CIFS SWN netlink\n\nCIFS_GENL_CMD_SWN_NOTIFY is the userspace witness-notify command.  The\nintended sender is the cifs.witness helper, but the generic-netlink\noperation currently has no capability flag, so any local process can send\nRESOURCE_CHANGE or CLIENT_MOVE notifications to the in-kernel witness\nhandler.\n\nThe same family exposes CIFS_GENL_MCGRP_SWN without multicast-group\ncapability flags.  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.  The\ncifs.witness service runs with the privileges needed for both operations."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"fed979a7e082bd9f25f9002c3c4f8740dacd0bc8","status":"affected","lessThan":"9cf7eb8919344932f909b2fac76296f7656fda8d","versionType":"git"},{"version":"fed979a7e082bd9f25f9002c3c4f8740dacd0bc8","status":"affected","lessThan":"9919021a3b7974ae66a5f9915e3a48c10cfd409b","versionType":"git"},{"version":"fed979a7e082bd9f25f9002c3c4f8740dacd0bc8","status":"affected","lessThan":"969bc6370334a5b4720c5470783295d6484bbc95","versionType":"git"},{"version":"fed979a7e082bd9f25f9002c3c4f8740dacd0bc8","status":"affected","lessThan":"a3238b09c58f323e40743ce174cd0ab81b5c09ed","versionType":"git"},{"version":"fed979a7e082bd9f25f9002c3c4f8740dacd0bc8","status":"affected","lessThan":"a8d17d22db591099519a89f14dd24810daba74c3","versionType":"git"},{"version":"fed979a7e082bd9f25f9002c3c4f8740dacd0bc8","status":"affected","lessThan":"c2397b93fbb6f44a788fff30f99be2c20cc5e50f","versionType":"git"},{"version":"fed979a7e082bd9f25f9002c3c4f8740dacd0bc8","status":"affected","lessThan":"d1ebfce2c1d161186a82e77590bf7da2ea1bce91","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/smb/client/netlink.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.11","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.11","versionType":"semver"},{"version":"5.15.210","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.176","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.143","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.92","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.34","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.11","status":"unaffected","lessThanOrEqual":"7.0.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/smb/client/netlink.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/9cf7eb8919344932f909b2fac76296f7656fda8d"},{"url":"https://git.kernel.org/stable/c/9919021a3b7974ae66a5f9915e3a48c10cfd409b"},{"url":"https://git.kernel.org/stable/c/969bc6370334a5b4720c5470783295d6484bbc95"},{"url":"https://git.kernel.org/stable/c/a3238b09c58f323e40743ce174cd0ab81b5c09ed"},{"url":"https://git.kernel.org/stable/c/a8d17d22db591099519a89f14dd24810daba74c3"},{"url":"https://git.kernel.org/stable/c/c2397b93fbb6f44a788fff30f99be2c20cc5e50f"},{"url":"https://git.kernel.org/stable/c/d1ebfce2c1d161186a82e77590bf7da2ea1bce91"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - Exploitation requires local access via generic-netlink syscalls (socket/bind/sendmsg/setsockopt on NETLINK_GENERIC), not remote SMB or network packet handling.\nAC:L - An unprivileged attacker can reliably join the SWN multicast group and send crafted SWN_NOTIFY commands; registration IDs are exposed in multicast register messages, with no races or uncontrollable conditions.\nPR:L - Before the fix, no capability checks guarded SWN_NOTIFY or multicast group membership, so any unprivileged local user could exploit without CAP_NET_ADMIN or user-namespace tricks.\nUI:N - Exploitation is passive (multicast subscription) or active (netlink injection) and does not require any victim action at attack time beyond pre-existing witness-enabled CIFS mounts.\nS:U - Impact is confined to the local kernel/CIFS client security domain (credential theft and connection manipulation); it does not cross VM, container, or IOMMU boundaries.\nC:H - Multicast register messages disclose NTLM username, domain, and plaintext password from active CIFS witness sessions to any local subscriber.\nI:H - Forged CLIENT_MOVE notifications redirect SMB reconnects to attacker-controlled endpoints, compromising connection integrity and enabling MITM against mounted cluster shares.\nA:H - Forged RESOURCE_CHANGE notifications force CIFS reconnect cycles on all channels, enabling reliable denial-of-service against witness-enabled mounts."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T12:39:38.366Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.11","versionEndExcluding":"5.15.210"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.11","versionEndExcluding":"6.1.176"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.11","versionEndExcluding":"6.6.143"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.11","versionEndExcluding":"6.12.92"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.11","versionEndExcluding":"6.18.34"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.11","versionEndExcluding":"7.0.11"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.11","versionEndExcluding":"7.1"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}