CVE-2025-68775
Full vulnerability record from the local CVENow database.
Description
In the Linux kernel, the following vulnerability has been resolved: net/handshake: duplicate handshake cancellations leak socket When a handshake request is cancelled it is removed from the handshake_net->hn_requests list, but it is still present in the handshake_rhashtbl until it is destroyed. If a second cancellation request arrives for the same handshake request, then remove_pending() will return false... and assuming HANDSHAKE_F_REQ_COMPLETED isn't set in req->hr_flags, we'll continue processing through the out_true label, where we put another reference on the sock and a refcount underflow occurs. This can happen for example if a handshake times out - particularly if the SUNRPC client sends the AUTH_TLS probe to the server but doesn't follow it up with the ClientHello due to a problem with tlshd. When the timeout is hit on the server, the server will send a FIN, which triggers a cancellation request via xs_reset_transport(). When the timeout is hit on the client, another cancellation request happens via xs_tls_handshake_sync(). Add a test_and_set_bit(HANDSHAKE_F_REQ_COMPLETED) in the pending cancel path so duplicate cancels can be detected.
Severity
CRITICAL
CVSS score
9.8
(v3.1)
Vulnerability status
Deferred
Source identifier
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Published
2026-01-13 16:15:57.073000
Last modified
2026-10-19 19:17:04.537000
View original CVE JSON
{
"id": "CVE-2025-68775",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"published": "2026-01-13T16:15:57.073",
"lastModified": "2026-10-19T19:17:04.537",
"vulnStatus": "Deferred",
"cveTags": [],
"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."
},
{
"lang": "es",
"value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nnet/handshake: las cancelaciones duplicadas de handshake fugan el socket\n\nCuando una solicitud de handshake es cancelada, es eliminada de la lista handshake_net->hn_requests, pero aún está presente en la handshake_rhashtbl hasta que es destruida.\n\nSi llega una segunda solicitud de cancelación para la misma solicitud de handshake, entonces remove_pending() devolverá falso... y asumiendo que HANDSHAKE_F_REQ_COMPLETED no está establecido en req->hr_flags, continuaremos procesando a través de la etiqueta out_true, donde ponemos otra referencia en el sock y ocurre un desbordamiento negativo del contador de referencias.\n\nEsto puede ocurrir por ejemplo si un handshake agota el tiempo de espera, particularmente si el cliente SUNRPC envía la sonda AUTH_TLS al servidor pero no la sigue con el ClientHello debido a un problema con tlshd. Cuando se alcanza el tiempo de espera en el servidor, el servidor enviará un FIN, lo que activa una solicitud de cancelación a través de xs_reset_transport(). Cuando se alcanza el tiempo de espera en el cliente, ocurre otra solicitud de cancelación a través de xs_tls_handshake_sync().\n\nAñadir un test_and_set_bit(HANDSHAKE_F_REQ_COMPLETED) en la ruta de cancelación pendiente para que las cancelaciones duplicadas puedan ser detectadas."
}
],
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
{
"vendor": "Linux",
"product": "Linux",
"defaultStatus": "unaffected",
"programFiles": [
"net/handshake/request.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"versions": [
{
"version": "3b3009ea8abb713b022d94fba95ec270cf6e7eae",
"lessThan": "011ae80c49d9bfa5b4336f8bd387cd25c7593663",
"versionType": "git",
"status": "affected"
},
{
"version": "3b3009ea8abb713b022d94fba95ec270cf6e7eae",
"lessThan": "e1641177e7fb48a0a5a06658d4aab51da6656659",
"versionType": "git",
"status": "affected"
},
{
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"lessThan": "3c330f1dee3cd92b57e19b9d21dc8ce5970b09be",
"versionType": "git",
"status": "affected"
},
{
"version": "3b3009ea8abb713b022d94fba95ec270cf6e7eae",
"lessThan": "15564bd67e2975002f2a8e9defee33e321d3183f",
"versionType": "git",
"status": "affected"
}
]
},
{
"vendor": "Linux",
"product": "Linux",
"defaultStatus": "affected",
"programFiles": [
"net/handshake/request.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"versions": [
{
"version": "6.4",
"status": "affected"
},
{
"version": "0",
"lessThan": "6.4",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.6.120",
"lessThanOrEqual": "6.6.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.12.64",
"lessThanOrEqual": "6.12.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.18.3",
"lessThanOrEqual": "6.18.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.19",
"lessThanOrEqual": "*",
"versionType": "original_commit_for_fix",
"status": "unaffected"
}
]
}
]
}
],
"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
}
],
"ssvcV203": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"ssvcData": {
"timestamp": "2026-10-16T15:05:12.016818Z",
"id": "CVE-2025-68775",
"options": [
{
"exploitation": "none"
},
{
"automatable": "yes"
},
{
"technicalImpact": "total"
}
],
"role": "CISA Coordinator",
"version": "2.0.3"
}
}
]
},
"weaknesses": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"type": "Secondary",
"description": [
{
"lang": "en",
"value": "CWE-662"
}
]
}
],
"references": [
{
"url": "https://git.kernel.org/stable/c/011ae80c49d9bfa5b4336f8bd387cd25c7593663",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/15564bd67e2975002f2a8e9defee33e321d3183f",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/3c330f1dee3cd92b57e19b9d21dc8ce5970b09be",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/e1641177e7fb48a0a5a06658d4aab51da6656659",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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}