{"id":"CVE-2025-68775","state":"PUBLISHED","title":"net/handshake: duplicate handshake cancellations leak socket","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/handshake: duplicate handshake cancellations leak socket\n\nWhen a handshake request is cancelled it is removed from the\nhandshake_net->hn_requests list, but it is still present in the\nhandshake_rhashtbl until it is destroyed.\n\nIf a second cancellation request arrives for the same handshake request,\nthen remove_pending() will return false... and assuming\nHANDSHAKE_F_REQ_COMPLETED isn't set in req->hr_flags, we'll continue\nprocessing through the out_true label, where we put another reference on\nthe sock and a refcount underflow occurs.\n\nThis can happen for example if a handshake times out - particularly if\nthe SUNRPC client sends the AUTH_TLS probe to the server but doesn't\nfollow it up with the ClientHello due to a problem with tlshd.  When the\ntimeout is hit on the server, the server will send a FIN, which triggers\na cancellation request via xs_reset_transport().  When the timeout is\nhit on the client, another cancellation request happens via\nxs_tls_handshake_sync().\n\nAdd a test_and_set_bit(HANDSHAKE_F_REQ_COMPLETED) in the pending cancel\npath so duplicate cancels can be detected.","publishedAt":"2026-01-13T15:28:52.069Z","updatedAt":"2026-10-19T18:05:06.829Z","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":"011ae80c49d9bfa5b4336f8bd387cd25c7593663","versionType":"git"},{"version":"3b3009ea8abb713b022d94fba95ec270cf6e7eae","status":"affected","lessThan":"e1641177e7fb48a0a5a06658d4aab51da6656659","versionType":"git"},{"version":"3b3009ea8abb713b022d94fba95ec270cf6e7eae","status":"affected","lessThan":"3c330f1dee3cd92b57e19b9d21dc8ce5970b09be","versionType":"git"},{"version":"3b3009ea8abb713b022d94fba95ec270cf6e7eae","status":"affected","lessThan":"15564bd67e2975002f2a8e9defee33e321d3183f","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["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":"6.6.120","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.64","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.3","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/handshake/request.c"]}],"references":["https://git.kernel.org/stable/c/011ae80c49d9bfa5b4336f8bd387cd25c7593663","https://git.kernel.org/stable/c/e1641177e7fb48a0a5a06658d4aab51da6656659","https://git.kernel.org/stable/c/3c330f1dee3cd92b57e19b9d21dc8ce5970b09be","https://git.kernel.org/stable/c/15564bd67e2975002f2a8e9defee33e321d3183f"],"weaknesses":["CWE-662"],"ingestedAt":"2026-10-29T20:09:56.034Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2025/68xxx/CVE-2025-68775.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2025-68775","state":"PUBLISHED","datePublished":"2026-01-13T15:28:52.069Z","dateUpdated":"2026-10-19T18:05:06.829Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2025-12-24T10:30:51.035Z"},"containers":{"cna":{"title":"net/handshake: duplicate handshake cancellations leak socket","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/handshake: duplicate handshake cancellations leak socket\n\nWhen a handshake request is cancelled it is removed from the\nhandshake_net->hn_requests list, but it is still present in the\nhandshake_rhashtbl until it is destroyed.\n\nIf a second cancellation request arrives for the same handshake request,\nthen remove_pending() will return false... and assuming\nHANDSHAKE_F_REQ_COMPLETED isn't set in req->hr_flags, we'll continue\nprocessing through the out_true label, where we put another reference on\nthe sock and a refcount underflow occurs.\n\nThis can happen for example if a handshake times out - particularly if\nthe SUNRPC client sends the AUTH_TLS probe to the server but doesn't\nfollow it up with the ClientHello due to a problem with tlshd.  When the\ntimeout is hit on the server, the server will send a FIN, which triggers\na cancellation request via xs_reset_transport().  When the timeout is\nhit on the client, another cancellation request happens via\nxs_tls_handshake_sync().\n\nAdd a test_and_set_bit(HANDSHAKE_F_REQ_COMPLETED) in the pending cancel\npath so duplicate cancels can be detected."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"3b3009ea8abb713b022d94fba95ec270cf6e7eae","status":"affected","lessThan":"011ae80c49d9bfa5b4336f8bd387cd25c7593663","versionType":"git"},{"version":"3b3009ea8abb713b022d94fba95ec270cf6e7eae","status":"affected","lessThan":"e1641177e7fb48a0a5a06658d4aab51da6656659","versionType":"git"},{"version":"3b3009ea8abb713b022d94fba95ec270cf6e7eae","status":"affected","lessThan":"3c330f1dee3cd92b57e19b9d21dc8ce5970b09be","versionType":"git"},{"version":"3b3009ea8abb713b022d94fba95ec270cf6e7eae","status":"affected","lessThan":"15564bd67e2975002f2a8e9defee33e321d3183f","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["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":"6.6.120","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.64","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.3","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/handshake/request.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/011ae80c49d9bfa5b4336f8bd387cd25c7593663"},{"url":"https://git.kernel.org/stable/c/e1641177e7fb48a0a5a06658d4aab51da6656659"},{"url":"https://git.kernel.org/stable/c/3c330f1dee3cd92b57e19b9d21dc8ce5970b09be"},{"url":"https://git.kernel.org/stable/c/15564bd67e2975002f2a8e9defee33e321d3183f"}],"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 client can reach the bug through a network-facing SUNRPC/NFS server by sending an AUTH_TLS NULL probe. TCP receive processing reaches svcauth_tls_accept(), svc_tcp_handshake(), and ultimately duplicate handshake cancellation.\nAC:L - The attacker can create and abandon concurrent AUTH_TLS connections to keep requests pending and drive both timeout and transport-teardown cancellations. No memory-layout guess or uncontrollable race is required.\nPR:N - AUTH_TLS is processed before RPC credentials are authenticated, and the probe requires no established identity, account, or kernel capability.\nUI:N - The server processes the probe, timeout, and socket teardown automatically without victim user action.\nS:U - Exploitation affects the same host-kernel security authority processing the request and does not cross a VM, IOMMU, or comparable security boundary.\nC:H - The extra sock_put() can prematurely free a still-referenced socket, producing a reclaimable kernel use-after-free capable of exposing arbitrary kernel memory.\nI:H - Reclaiming the prematurely freed socket object can provide attacker-controlled data to subsequent kernel accesses, enabling arbitrary modification or control-flow hijacking.\nA:H - The socket use-after-free can cause a kernel oops or panic, while repeated unauthenticated triggers can also leak sockets and exhaust resources."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T12:11:25.376Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.4","versionEndExcluding":"6.6.120"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.4","versionEndExcluding":"6.12.64"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.4","versionEndExcluding":"6.18.3"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.4","versionEndExcluding":"6.19"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2025-68775","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"total"}],"version":"2.0.3","timestamp":"2026-10-16T15:05:12.016818Z"}}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-662","lang":"en","type":"CWE","description":"CWE-662 Improper Synchronization"}]}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-19T18:05:06.829Z"}}]}}}