{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-89536", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-11T19:38:34.721Z", "datePublished": "2026-09-11T19:44:14.473Z", "dateUpdated": "2026-10-19T08:48:28.030Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T08:48:28.030Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nSUNRPC: wait for in-flight client TLS handshake callback\n\nxs_tls_handshake_sync() gives xs_tls_handshake_done() a reference to the\nlower transport before submitting the handshake request. On timeout or\nsignal, the synchronous waiter drops that reference after calling\ntls_handshake_cancel().\n\nhandshake_req_cancel() returns false when handshake_complete() has\nalready marked the request complete. In that case the completion callback\ncan still be running, so dropping the callback-owned reference in the\nwaiter can free the lower transport before xs_tls_handshake_done() stores\nxprt_err or drops its own reference.\n\nIf cancellation loses to completion, wait until xs_tls_handshake_done()\nsignals handshake_done and let the callback release its reference. This\nmirrors the server-side handshake lifetime handling and keeps the timeout\nor signal return value unchanged." } ], "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 - The bug is in the SUNRPC TCP-with-TLS client handshake (xs_tls_handshake_sync), reached when a remote NFS/RPC peer completes RPC-with-TLS; a malicious server or on-path attacker with xprtsec=tls (anonymous TLS) drives handshake_complete() over the network against the client's 10s wait.\nAC:L - The attacker times TLS completion against the fixed XS_TLS_HANDSHAKE_TO window and can force repeated reconnects so tls_handshake_cancel() losing to handshake_complete() is reliably hittable, with no memory-layout guess or other condition outside attacker control.\nPR:N - No privileges on the victim host are required; a remote TLS peer only needs the client to initiate or re-establish an RPC-with-TLS connection, and the handshake runs after AUTH_TLS STARTTLS but before NFS credentials are verified.\nUI:N - No victim action is needed at attack time once an NFS xprtsec=tls/mtls mount exists, because idle disconnect or server-induced reconnect automatically re-enters xs_tcp_tls_setup_socket() and the handshake wait.\nS:U - The use-after-free corrupts kernel heap state in the SUNRPC client on the same host; impact stays within that kernel's security authority and does not cross a VM, IOMMU, or sandbox boundary.\nC:H - When cancel loses, the waiter still xprt_put()s the callback-owned rpc_xprt reference, so sock_xprt can be freed while xs_tls_handshake_done() writes xprt_err and the connect worker still uses lower_xprt, a heap UAF enabling arbitrary disclosure.\nI:H - Use-after-free of rpc_xprt/sock_xprt (ops pointers, wait queues, socket state) allows heap reuse for arbitrary writes and control-flow hijacking, not merely a crash.\nA:H - The extra put can destroy the transport while the handshake waiter and connect worker still touch it, producing a kernel oops/panic or a hang in xprt_destroy waiting on XPRT_LOCKED, denying NFS/RPC service." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/sunrpc/xprtsock.c" ], "versions": [ { "version": "75eb6af7acdf566c68d61e98e67ee2f235201c02", "lessThan": "fb43997407bc17ee39bac81ab708101312e255f5", "status": "affected", "versionType": "git" }, { "version": "75eb6af7acdf566c68d61e98e67ee2f235201c02", "lessThan": "15431820f448e09f8029b670d5c82aa5917d4625", "status": "affected", "versionType": "git" }, { "version": "75eb6af7acdf566c68d61e98e67ee2f235201c02", "lessThan": "1de391e8b94e31b45c19c16dbf315e294810c7de", "status": "affected", "versionType": "git" }, { "version": "75eb6af7acdf566c68d61e98e67ee2f235201c02", "lessThan": "7fbb6d2ab0391eb8d1f1a68e6bc263ef02cea61b", "status": "affected", "versionType": "git" }, { "version": "75eb6af7acdf566c68d61e98e67ee2f235201c02", "lessThan": "a89dd597458848b463d284b15e42a8078beeb046", "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/sunrpc/xprtsock.c" ], "versions": [ { "version": "6.5", "status": "affected" }, { "version": "0", "lessThan": "6.5", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.157", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.109", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.50", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2.4", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.3", "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": "6.5", "versionEndExcluding": "6.6.157" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.5", "versionEndExcluding": "6.12.109" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.5", "versionEndExcluding": "6.18.50" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.5", "versionEndExcluding": "7.2.4" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.5", "versionEndExcluding": "7.3" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/fb43997407bc17ee39bac81ab708101312e255f5" }, { "url": "https://git.kernel.org/stable/c/15431820f448e09f8029b670d5c82aa5917d4625" }, { "url": "https://git.kernel.org/stable/c/1de391e8b94e31b45c19c16dbf315e294810c7de" }, { "url": "https://git.kernel.org/stable/c/7fbb6d2ab0391eb8d1f1a68e6bc263ef02cea61b" }, { "url": "https://git.kernel.org/stable/c/a89dd597458848b463d284b15e42a8078beeb046" } ], "title": "SUNRPC: wait for in-flight client TLS handshake callback", "x_generator": { "engine": "bippy-1.2.0" } } } }