{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-64523", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-07-19T15:36:31.794Z", "datePublished": "2026-07-25T09:20:47.606Z", "dateUpdated": "2026-08-09T18:34:58.632Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-09T18:34:58.632Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/handshake: Take a long-lived file reference at submit\n\nhandshake_nl_accept_doit() needs the file pointer backing\nreq->hr_sk->sk_socket to survive the window between\nhandshake_req_next() and the subsequent FD_PREPARE() and get_file().\nThe submit-side sock_hold() does not provide that. sk_refcnt keeps\nstruct sock alive, but struct socket is owned by sock->file: when\nthe consumer fputs the last file reference, sock_release() tears\nthe socket down regardless of any sock_hold.\n\nAdd an hr_file pointer to struct handshake_req and acquire an\nexplicit reference on sock->file during handshake_req_submit().\nhandshake_complete() and handshake_req_cancel() release the\nreference on the completion-bit-winning path.\n\nThe submit error path must also release the file reference, but\nafter rhashtable insertion a concurrent handshake_req_cancel() can\ndiscover the request and race the error path. Gate the error-path\ncleanup -- sk_destruct restoration, fput, and request destruction\n-- with test_and_set_bit(HANDSHAKE_F_REQ_COMPLETED), the same\nserialization handshake_complete() and handshake_req_cancel()\nalready use. When cancel has already claimed ownership, the submit\nerror path returns without touching the request; socket teardown\nhandles final destruction.\n\nThe accept-side dereferences are not yet retargeted; that change\ncomes in the next patch." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 9.8, "baseSeverity": "CRITICAL" }, "scenarios": [ { "lang": "en", "value": "AV:N - An unauthenticated remote peer can make network-facing NFS/RPC-over-TLS or TLS-enabled NVMe/TCP consumers submit a handshake, then disconnect or force timeout while tlshd accepts it.\nAC:L - Connection churn lets the attacker repeatedly create handshake requests and drive cancellation while the normal agent accepts; no secret state or uncontrollable memory layout is required.\nPR:N - The RPC_AUTH_TLS probe and NVMe/TCP TLS setup occur before peer authentication. ACCEPT requires init-namespace CAP_NET_ADMIN, but trusted tlshd issues it automatically rather than the attacker.\nUI:N - Kernel consumers and the handshake daemon process the request automatically without any victim user action.\nS:U - Exploitation compromises resources governed by the same host-kernel security authority and does not inherently cross a VM, IOMMU, or other security boundary.\nC:H - The race can dereference reclaimed socket, file, or handshake-request memory; heap reuse of this UAF can provide access to arbitrary kernel data.\nI:H - The stale file pointer reaches refcount-writing operations such as get_file(), while reclaimed request data includes callback pointers, making arbitrary writes or control-flow hijacking defensible.\nA:H - The NULL dereference or use-after-free can cause a kernel oops or panic, and a remote attacker can trigger the race repeatedly." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/handshake/handshake.h", "net/handshake/netlink.c", "net/handshake/request.c" ], "versions": [ { "version": "3b3009ea8abb713b022d94fba95ec270cf6e7eae", "lessThan": "685b10dd0e32c7782cead16c8cf055c609678583", "status": "affected", "versionType": "git" }, { "version": "3b3009ea8abb713b022d94fba95ec270cf6e7eae", "lessThan": "b913801ad9b9a51437d84d030ec6843e08976bd6", "status": "affected", "versionType": "git" }, { "version": "3b3009ea8abb713b022d94fba95ec270cf6e7eae", "lessThan": "16eaba5aa89c04eea125905bb8f988c1897f4f29", "status": "affected", "versionType": "git" }, { "version": "3b3009ea8abb713b022d94fba95ec270cf6e7eae", "lessThan": "09dba37eee70d0596e26645015f1aa95a9848e9d", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/handshake/handshake.h", "net/handshake/netlink.c", "net/handshake/request.c" ], "versions": [ { "version": "6.4", "status": "affected" }, { "version": "0", "lessThan": "6.4", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.93", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.44", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.0.12", "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": "6.4", "versionEndExcluding": "6.12.93" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.4", "versionEndExcluding": "6.18.44" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.4", "versionEndExcluding": "7.0.12" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.4", "versionEndExcluding": "7.1" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/685b10dd0e32c7782cead16c8cf055c609678583" }, { "url": "https://git.kernel.org/stable/c/b913801ad9b9a51437d84d030ec6843e08976bd6" }, { "url": "https://git.kernel.org/stable/c/16eaba5aa89c04eea125905bb8f988c1897f4f29" }, { "url": "https://git.kernel.org/stable/c/09dba37eee70d0596e26645015f1aa95a9848e9d" } ], "title": "net/handshake: Take a long-lived file reference at submit", "x_generator": { "engine": "bippy-1.2.0" } } } }