{"api_version":"1","generated_at":"2026-07-23T18:01:34+00:00","cve":"CVE-2026-63979","urls":{"html":"https://cve.report/CVE-2026-63979","api":"https://cve.report/api/cve/CVE-2026-63979.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-63979","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-63979"},"summary":{"title":"net/handshake: hand off the pinned file reference to accept_doit","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/handshake: hand off the pinned file reference to accept_doit\n\nhandshake_req_next() removes the request from the per-net\npending list and drops hn_lock before handshake_nl_accept_doit()\nreads req->hr_sk->sk_socket and dereferences sock->file (once in\nFD_PREPARE() and again in get_file()).  In that window a\nconsumer running tls_handshake_cancel() followed by sockfd_put()\n(svc_sock_free) or __fput_sync() (xs_reset_transport) releases\nsock->file.  sock_release() then runs sock_orphan(), zeroing\nsk_socket, and frees the struct socket.  The accept-side code\neither reads NULL through sk_socket or chases freed memory.\n\nThe submit-side sock_hold() does not prevent this.  sk_refcnt\nprotects struct sock, but struct socket and sock->file are\nindependently refcounted via the file descriptor the consumer\nowns.  Pinning sk leaves sock and sock->file unprotected.\n\nRetarget the accept-side dereferences at req->hr_file, which was\npinned at submit time, instead of req->hr_sk->sk_socket->file.\nPinning on its own is not sufficient: a consumer that cancels\nbetween handshake_req_next() returning and accept_doit reaching\nFD_PREPARE() takes the !remove_pending() branch in\nhandshake_req_cancel() and drops hr_file before the accept side\ntakes its own reference.  Hand off an additional file reference\ninside handshake_req_next(), under hn_lock, so the accept side\noperates on a reference that no concurrent handshake_req_cancel()\ncan revoke.  FD_PREPARE() consumes that handed-off reference,\neither by transferring it to the new fd in fd_publish() or by\ndropping it in the cleanup destructor on error; the explicit\nget_file() that previously balanced FD_PREPARE() is therefore\nredundant and goes away.\n\nUpdate handshake_req_cancel_test2 and _test3 to simulate the\nFD_PREPARE() consumption with an fput() so the kunit file-count\nassertions stay balanced.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-07-19 16:17:17","updated_at":"2026-07-20 15:17:00"},"problem_types":[],"metrics":[{"version":"3.1","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","score":"9.8","severity":"CRITICAL","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","data":{"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","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"}},{"version":"3.1","source":"CNA","type":"DECLARED","score":"9.8","severity":"CRITICAL","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","data":{"baseScore":9.8,"baseSeverity":"CRITICAL","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","version":"3.1"}}],"references":[{"url":"https://git.kernel.org/stable/c/c06876d4fac38f35820946ee3b1be7d7da799cd4","name":"https://git.kernel.org/stable/c/c06876d4fac38f35820946ee3b1be7d7da799cd4","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/f4251190e58b209999c1ba9e6d2976136a1be055","name":"https://git.kernel.org/stable/c/f4251190e58b209999c1ba9e6d2976136a1be055","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-63979","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-63979","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 3b3009ea8abb713b022d94fba95ec270cf6e7eae c06876d4fac38f35820946ee3b1be7d7da799cd4 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 3b3009ea8abb713b022d94fba95ec270cf6e7eae f4251190e58b209999c1ba9e6d2976136a1be055 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.4","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.4 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.0.12 7.0.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.1 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"63979","cve":"CVE-2026-63979","epss":"0.001890000","percentile":"0.087830000","score_date":"2026-07-20","updated_at":"2026-07-21 00:13:13"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["net/handshake/handshake-test.c","net/handshake/netlink.c","net/handshake/request.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"c06876d4fac38f35820946ee3b1be7d7da799cd4","status":"affected","version":"3b3009ea8abb713b022d94fba95ec270cf6e7eae","versionType":"git"},{"lessThan":"f4251190e58b209999c1ba9e6d2976136a1be055","status":"affected","version":"3b3009ea8abb713b022d94fba95ec270cf6e7eae","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["net/handshake/handshake-test.c","net/handshake/netlink.c","net/handshake/request.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"6.4"},{"lessThan":"6.4","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"7.0.*","status":"unaffected","version":"7.0.12","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.1","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.0.12","versionStartIncluding":"6.4","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.1","versionStartIncluding":"6.4","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/handshake: hand off the pinned file reference to accept_doit\n\nhandshake_req_next() removes the request from the per-net\npending list and drops hn_lock before handshake_nl_accept_doit()\nreads req->hr_sk->sk_socket and dereferences sock->file (once in\nFD_PREPARE() and again in get_file()).  In that window a\nconsumer running tls_handshake_cancel() followed by sockfd_put()\n(svc_sock_free) or __fput_sync() (xs_reset_transport) releases\nsock->file.  sock_release() then runs sock_orphan(), zeroing\nsk_socket, and frees the struct socket.  The accept-side code\neither reads NULL through sk_socket or chases freed memory.\n\nThe submit-side sock_hold() does not prevent this.  sk_refcnt\nprotects struct sock, but struct socket and sock->file are\nindependently refcounted via the file descriptor the consumer\nowns.  Pinning sk leaves sock and sock->file unprotected.\n\nRetarget the accept-side dereferences at req->hr_file, which was\npinned at submit time, instead of req->hr_sk->sk_socket->file.\nPinning on its own is not sufficient: a consumer that cancels\nbetween handshake_req_next() returning and accept_doit reaching\nFD_PREPARE() takes the !remove_pending() branch in\nhandshake_req_cancel() and drops hr_file before the accept side\ntakes its own reference.  Hand off an additional file reference\ninside handshake_req_next(), under hn_lock, so the accept side\noperates on a reference that no concurrent handshake_req_cancel()\ncan revoke.  FD_PREPARE() consumes that handed-off reference,\neither by transferring it to the new fd in fd_publish() or by\ndropping it in the cleanup destructor on error; the explicit\nget_file() that previously balanced FD_PREPARE() is therefore\nredundant and goes away.\n\nUpdate handshake_req_cancel_test2 and _test3 to simulate the\nFD_PREPARE() consumption with an fput() so the kunit file-count\nassertions stay balanced."}],"metrics":[{"cvssV3_1":{"baseScore":9.8,"baseSeverity":"CRITICAL","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","version":"3.1"}}],"providerMetadata":{"dateUpdated":"2026-07-20T13:42:03.030Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/c06876d4fac38f35820946ee3b1be7d7da799cd4"},{"url":"https://git.kernel.org/stable/c/f4251190e58b209999c1ba9e6d2976136a1be055"}],"title":"net/handshake: hand off the pinned file reference to accept_doit","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-63979","datePublished":"2026-07-19T14:56:03.177Z","dateReserved":"2026-07-19T07:54:57.025Z","dateUpdated":"2026-07-20T13:42:03.030Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-07-19 16:17:17","lastModifiedDate":"2026-07-20 15:17:00","problem_types":[],"metrics":{"cvssMetricV31":[{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","cvssData":{"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","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":3.9,"impactScore":5.9}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"63979","Ordinal":"1","Title":"net/handshake: hand off the pinned file reference to accept_doit","CVE":"CVE-2026-63979","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"63979","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/handshake: hand off the pinned file reference to accept_doit\n\nhandshake_req_next() removes the request from the per-net\npending list and drops hn_lock before handshake_nl_accept_doit()\nreads req->hr_sk->sk_socket and dereferences sock->file (once in\nFD_PREPARE() and again in get_file()).  In that window a\nconsumer running tls_handshake_cancel() followed by sockfd_put()\n(svc_sock_free) or __fput_sync() (xs_reset_transport) releases\nsock->file.  sock_release() then runs sock_orphan(), zeroing\nsk_socket, and frees the struct socket.  The accept-side code\neither reads NULL through sk_socket or chases freed memory.\n\nThe submit-side sock_hold() does not prevent this.  sk_refcnt\nprotects struct sock, but struct socket and sock->file are\nindependently refcounted via the file descriptor the consumer\nowns.  Pinning sk leaves sock and sock->file unprotected.\n\nRetarget the accept-side dereferences at req->hr_file, which was\npinned at submit time, instead of req->hr_sk->sk_socket->file.\nPinning on its own is not sufficient: a consumer that cancels\nbetween handshake_req_next() returning and accept_doit reaching\nFD_PREPARE() takes the !remove_pending() branch in\nhandshake_req_cancel() and drops hr_file before the accept side\ntakes its own reference.  Hand off an additional file reference\ninside handshake_req_next(), under hn_lock, so the accept side\noperates on a reference that no concurrent handshake_req_cancel()\ncan revoke.  FD_PREPARE() consumes that handed-off reference,\neither by transferring it to the new fd in fd_publish() or by\ndropping it in the cleanup destructor on error; the explicit\nget_file() that previously balanced FD_PREPARE() is therefore\nredundant and goes away.\n\nUpdate handshake_req_cancel_test2 and _test3 to simulate the\nFD_PREPARE() consumption with an fput() so the kunit file-count\nassertions stay balanced.","Type":"Description","Title":"net/handshake: hand off the pinned file reference to accept_doit"}]}}}