{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-72221", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-08-09T03:40:39.913Z", "datePublished": "2026-08-15T05:54:14.539Z", "dateUpdated": "2026-08-17T05:41:42.766Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-17T05:41:42.766Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsunrpc: wait for in-flight TLS handshake callback when cancel loses race\n\nWhen wait_for_completion_interruptible_timeout() in\nsvc_tcp_handshake() returns 0 (timeout) or -ERESTARTSYS (signal) and\ntls_handshake_cancel() then returns false, handshake_complete() has\nwon the cancellation race: it has set HANDSHAKE_F_REQ_COMPLETED and\nis about to invoke svc_tcp_handshake_done(), but the callback's\nside effects on xpt_flags and on svsk->sk_handshake_done have not\nyet committed.\n\nThe current code reads xpt_flags immediately to decide whether the\nsession succeeded. Two races result.\n\nIf the callback has executed set_bit(XPT_TLS_SESSION) but not yet\nclear_bit(XPT_HANDSHAKE), svc_tcp_handshake() sees a session,\nenqueues the transport, and returns. svc_xprt_received() then\nclears XPT_BUSY, a worker thread picks the transport up, the\ndispatcher in svc_handle_xprt() observes XPT_HANDSHAKE still set,\nand xpo_handshake is invoked a second time. That svc_tcp_handshake()\ncalls init_completion(&svsk->sk_handshake_done) while the original\ncallback concurrently calls complete_all() on it, corrupting the\nembedded swait_queue.\n\nIf the callback has set HANDSHAKE_F_REQ_COMPLETED but not yet\nentered svc_tcp_handshake_done(), svc_tcp_handshake() reads\nXPT_TLS_SESSION as clear and tears the connection down even though\nthe handshake is about to succeed.\n\nWait for the callback to commit before inspecting xpt_flags. The\ncompletion is guaranteed to fire because handshake_complete()\ninvokes svc_tcp_handshake_done() unconditionally once it has set\nHANDSHAKE_F_REQ_COMPLETED." } ], "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 - Reachable over TCP by any remote peer of an in-kernel NFS/RPC server (nfsd) via the pre-auth RPC_AUTH_TLS NULL-procedure STARTTLS path that invokes svc_tcp_handshake() on the accepted SUNRPC transport.\nAC:L - The attacker controls both sides of the race by timing TLS client handshake messages against the fixed 5-second SVC_HANDSHAKE_TO and opening many parallel connections to reliably hit the cancel-lost window.\nPR:N - No credentials or export authorization are required; svcauth_tls_accept() accepts empty AUTH_TLS on RPC NULL from any TCP client, and svcauth_unix_set_client() skips IP export checks when rq_proc==0.\nUI:N - Exploitation requires only scripted network connections and TLS client traffic to nfsd; no victim user interaction such as mounting a filesystem or opening a file is needed.\nS:U - Memory corruption occurs in nfsd kernel worker context on the same host; impact is kernel privilege compromise within the server security authority, not a VM escape or IOMMU boundary bypass.\nC:H - A second svc_tcp_handshake() can call init_completion() while svc_tcp_handshake_done() concurrently calls complete_all(), corrupting the embedded swait_queue in heap-allocated svc_sock and enabling arbitrary kernel memory disclosure.\nI:H - Corrupting completion wait-queue metadata in the svc_sock heap object can be leveraged for arbitrary kernel writes and control-flow hijacking to achieve local privilege escalation on the NFS server.\nA:H - The swait_queue corruption can trigger kernel oops/panic, and the alternate race path tears down connections whose TLS handshake is about to succeed, enabling repeatable remote denial-of-service against nfsd." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/sunrpc/svcsock.c" ], "versions": [ { "version": "b3cbf98e2fdf3cb147a95161560cd25987284330", "lessThan": "0d8ceb39884148dc7a2fdf71e1cac5961ed1d2b9", "status": "affected", "versionType": "git" }, { "version": "b3cbf98e2fdf3cb147a95161560cd25987284330", "lessThan": "e0f4691d42a54d359d8b64509fd9ab938d4f2a33", "status": "affected", "versionType": "git" }, { "version": "b3cbf98e2fdf3cb147a95161560cd25987284330", "lessThan": "65b23bec1fca6e9ebdc3e6041ebf8c6ab074141b", "status": "affected", "versionType": "git" }, { "version": "b3cbf98e2fdf3cb147a95161560cd25987284330", "lessThan": "a4f878e8ecd729ccf2e50993444e217583adeace", "status": "affected", "versionType": "git" }, { "version": "b3cbf98e2fdf3cb147a95161560cd25987284330", "lessThan": "d00e32f84ca1a77cb67a3fbf59f58dada95f5a21", "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/svcsock.c" ], "versions": [ { "version": "6.4", "status": "affected" }, { "version": "0", "lessThan": "6.4", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.145", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.97", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.40", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1.5", "lessThanOrEqual": "7.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2", "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": "6.6.145" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.4", "versionEndExcluding": "6.12.97" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.4", "versionEndExcluding": "6.18.40" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.4", "versionEndExcluding": "7.1.5" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.4", "versionEndExcluding": "7.2" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/0d8ceb39884148dc7a2fdf71e1cac5961ed1d2b9" }, { "url": "https://git.kernel.org/stable/c/e0f4691d42a54d359d8b64509fd9ab938d4f2a33" }, { "url": "https://git.kernel.org/stable/c/65b23bec1fca6e9ebdc3e6041ebf8c6ab074141b" }, { "url": "https://git.kernel.org/stable/c/a4f878e8ecd729ccf2e50993444e217583adeace" }, { "url": "https://git.kernel.org/stable/c/d00e32f84ca1a77cb67a3fbf59f58dada95f5a21" } ], "title": "sunrpc: wait for in-flight TLS handshake callback when cancel loses race", "x_generator": { "engine": "bippy-1.2.0" } } } }