{"id":"CVE-2026-64523","state":"PUBLISHED","title":"net/handshake: Take a long-lived file reference at submit","description":"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.","publishedAt":"2026-07-25T09:20:47.606Z","updatedAt":"2026-10-21T12:43:25.473Z","severity":{"score":9.8,"label":"Critical","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/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":"3b3009ea8abb713b022d94fba95ec270cf6e7eae","status":"affected","lessThan":"22e371a93563c30ebebc576db049785e0d7fc617","versionType":"git"},{"version":"3b3009ea8abb713b022d94fba95ec270cf6e7eae","status":"affected","lessThan":"685b10dd0e32c7782cead16c8cf055c609678583","versionType":"git"},{"version":"3b3009ea8abb713b022d94fba95ec270cf6e7eae","status":"affected","lessThan":"b913801ad9b9a51437d84d030ec6843e08976bd6","versionType":"git"},{"version":"3b3009ea8abb713b022d94fba95ec270cf6e7eae","status":"affected","lessThan":"16eaba5aa89c04eea125905bb8f988c1897f4f29","versionType":"git"},{"version":"3b3009ea8abb713b022d94fba95ec270cf6e7eae","status":"affected","lessThan":"09dba37eee70d0596e26645015f1aa95a9848e9d","versionType":"git"}],"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"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.4","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.4","versionType":"semver"},{"version":"6.6.160","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.93","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.44","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.12","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":["net/handshake/handshake.h","net/handshake/netlink.c","net/handshake/request.c"]}],"references":["https://git.kernel.org/stable/c/22e371a93563c30ebebc576db049785e0d7fc617","https://git.kernel.org/stable/c/685b10dd0e32c7782cead16c8cf055c609678583","https://git.kernel.org/stable/c/b913801ad9b9a51437d84d030ec6843e08976bd6","https://git.kernel.org/stable/c/16eaba5aa89c04eea125905bb8f988c1897f4f29","https://git.kernel.org/stable/c/09dba37eee70d0596e26645015f1aa95a9848e9d"],"weaknesses":["CWE-416"],"ingestedAt":"2026-10-29T20:12:41.951Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/64xxx/CVE-2026-64523.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-64523","state":"PUBLISHED","datePublished":"2026-07-25T09:20:47.606Z","dateUpdated":"2026-10-21T12:43:25.473Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-07-19T15:36:31.794Z"},"containers":{"cna":{"title":"net/handshake: Take a long-lived file reference at submit","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."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"3b3009ea8abb713b022d94fba95ec270cf6e7eae","status":"affected","lessThan":"22e371a93563c30ebebc576db049785e0d7fc617","versionType":"git"},{"version":"3b3009ea8abb713b022d94fba95ec270cf6e7eae","status":"affected","lessThan":"685b10dd0e32c7782cead16c8cf055c609678583","versionType":"git"},{"version":"3b3009ea8abb713b022d94fba95ec270cf6e7eae","status":"affected","lessThan":"b913801ad9b9a51437d84d030ec6843e08976bd6","versionType":"git"},{"version":"3b3009ea8abb713b022d94fba95ec270cf6e7eae","status":"affected","lessThan":"16eaba5aa89c04eea125905bb8f988c1897f4f29","versionType":"git"},{"version":"3b3009ea8abb713b022d94fba95ec270cf6e7eae","status":"affected","lessThan":"09dba37eee70d0596e26645015f1aa95a9848e9d","versionType":"git"}],"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"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.4","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.4","versionType":"semver"},{"version":"6.6.160","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.93","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.44","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.12","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":["net/handshake/handshake.h","net/handshake/netlink.c","net/handshake/request.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/22e371a93563c30ebebc576db049785e0d7fc617"},{"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"}],"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."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-21T12:43:25.473Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.4","versionEndExcluding":"6.6.160"},{"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"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-64523","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"total"}],"version":"2.0.3","timestamp":"2026-10-16T15:41:36.840538Z"}}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-416","lang":"en","type":"CWE","description":"CWE-416 Use After Free"}]}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-19T20:48:37.874Z"}}]}}}