{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-64137", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-07-19T07:54:57.037Z", "datePublished": "2026-07-19T15:40:31.045Z", "dateUpdated": "2026-08-05T12:39:38.366Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:39:38.366Z" }, "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." } ], "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." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/smb/client/netlink.c" ], "versions": [ { "version": "fed979a7e082bd9f25f9002c3c4f8740dacd0bc8", "lessThan": "9cf7eb8919344932f909b2fac76296f7656fda8d", "status": "affected", "versionType": "git" }, { "version": "fed979a7e082bd9f25f9002c3c4f8740dacd0bc8", "lessThan": "9919021a3b7974ae66a5f9915e3a48c10cfd409b", "status": "affected", "versionType": "git" }, { "version": "fed979a7e082bd9f25f9002c3c4f8740dacd0bc8", "lessThan": "969bc6370334a5b4720c5470783295d6484bbc95", "status": "affected", "versionType": "git" }, { "version": "fed979a7e082bd9f25f9002c3c4f8740dacd0bc8", "lessThan": "a3238b09c58f323e40743ce174cd0ab81b5c09ed", "status": "affected", "versionType": "git" }, { "version": "fed979a7e082bd9f25f9002c3c4f8740dacd0bc8", "lessThan": "a8d17d22db591099519a89f14dd24810daba74c3", "status": "affected", "versionType": "git" }, { "version": "fed979a7e082bd9f25f9002c3c4f8740dacd0bc8", "lessThan": "c2397b93fbb6f44a788fff30f99be2c20cc5e50f", "status": "affected", "versionType": "git" }, { "version": "fed979a7e082bd9f25f9002c3c4f8740dacd0bc8", "lessThan": "d1ebfce2c1d161186a82e77590bf7da2ea1bce91", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/smb/client/netlink.c" ], "versions": [ { "version": "5.11", "status": "affected" }, { "version": "0", "lessThan": "5.11", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.210", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.176", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.143", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.92", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.34", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.0.11", "lessThanOrEqual": "7.0.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "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" } ] } ] } ], "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" } ], "title": "smb: client: require net admin for CIFS SWN netlink", "x_generator": { "engine": "bippy-1.2.0" } } } }