{"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"}}}}