CVE-2026-72473
In the Linux kernel, the following vulnerability has been resolved:
xprtrdma: Decouple req recycling from RPC completion
rl_kref formerly served two distinct lifetimes through a single refcount: it gated when a Reply could wake its RPC task, and it gated when an rpcrdma_req could return to its free pool. The marshal path took the Send-side reference only when SGEs needed DMA-unmap (sc_unmap_count > 0), which made a Send carrying only pre-registered buffers an exception: the Reply handler dropped rl_kref from 1 to 0 and freed the req while the HCA might still be DMA-reading from its send buffer.
Give rl_kref a narrower job. The RPC layer takes one reference when slot allocation hands a req out. rpcrdma_prepare_send_sges() takes a Send-side reference unconditionally after WR preparation succeeds. xprt_rdma_free_slot() and xprt_rdma_bc_free_rqst() drop the RPC-layer reference; rpcrdma_sendctx_unmap() drops the Send-side reference. The req returns to its free pool only after both owners have signed off.
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The existing kref_init(&req->rl_kref) call in rpcrdma_prepare_send_sges() is removed. Initialization moves to the slot-allocation paths (xprt_rdma_alloc_slot and rpcrdma_bc_rqst_get), and the release callback re-arms rl_kref before the req returns to a free pool. A re-init in the marshal path would discard the RPC-layer reference that already exists on entry.
Three invariants follow:
Replies now complete the RPC directly. rpcrdma_reply_handler() calls rpcrdma_complete_rqst() in place of kref_put on the non-LocalInv branch. The LocalInv branch already completes the RPC from frwr_unmap_async() and is unaffected.
Because Send-side references can now outlive RPC completion, connection teardown drains sendctx entries whose unsignaled Sends never had a later signaled completion to walk the ring. rpcrdma_sendctxs_destroy() walks the active range and runs rpcrdma_sendctx_unmap() on each entry with a non-NULL sc_req before the request buffers are reset, and is moved ahead of rpcrdma_reqs_reset() in rpcrdma_xprt_disconnect() so the reqs are still in their pre-reset state when the Send-side refs are released.
The drain creates a teardown-ordering hazard on the backchannel path. With the new lifetime, releasing a bc_prealloc req from rpcrdma_req_release() re-adds it to bc_pa_list. The disconnect in xprt_rdma_destroy() runs after xprt_destroy_backchannel() has already emptied bc_pa_list, so the drained reqs would otherwise leak. xprt_rdma_destroy() now runs xprt_rdma_bc_destroy(xprt, 0) a second time after the disconnect to reclaim them.
Detalles técnicos trazas, registros y código del informe original
- Any rpcrdma_req held by an rpc_rqst has rl_kref >= 1.
xprt_rdma_alloc_slot(), rpcrdma_bc_rqst_get(), and the
backlog-wake branch in xprt_rdma_alloc_slot() each kref_init
rl_kref before publishing the req. Without this invariant,
an RPC task that aborts between slot allocation and marshal
(gss_refresh failure or signal during call_connect, for
example) would drive xprt_release() ->
xprt_rdma_free_slot() -> kref_put against a refcount of
zero, saturating refcount_t and stranding the slot.
- The Send-side reference is taken only after WR prep
succeeds. A mapping failure in rpcrdma_prepare_send_sges()
runs rpcrdma_sendctx_cancel(), which DMA-unmaps the sendctx
and clears sc_req without touching rl_kref. The sendctx
ring walks in rpcrdma_sendctx_put_locked() and
rpcrdma_sendctxs_destroy() skip entries with sc_req == NULL,
so a burst of -EIO marshal failures cannot hold reqs off
rb_send_bufs.
- The release callback re-arms rl_kref so the next consumer
enters with the invariant satisfied.CVSS
- Versión: 3.1
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Puntuación base: 9.8
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.72%
- Percentil entre todas las CVEs puntuadas: 52
- Fecha de la puntuación: 5/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
🎯 Técnicas ATT&CK
Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.
- Explotación
T1190Exploit Public-Facing Applicationinitial access75 % - Impacto principal
T1499.004Application or System Exploitationimpact70 %
Vulnerabilidad de kernel Linux en RDMA con vector de red sin autenticación (AV:N/PR:N) que permite DoS por crash/corrupción de memoria; explotable remotamente como T1190. Impactos: denegación de servicio (T1499.004 crash) y posible corrupción de datos en memoria compartida (T1561.002).
Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.
🛡️ Mitigaciones ATT&CK que cubren estas técnicas
Tecnologías afectadas (1)
⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.
Referencias
- https://git.kernel.org/stable/c/53442c7d0c888e51b8bc3da196970a669cc6b294
- https://git.kernel.org/stable/c/740975054a1970c0cf15f70ac39724a064f45847
- https://git.kernel.org/stable/c/8203f760a72bd39a3b66bc4eff0aa272a99fe22b
- https://git.kernel.org/stable/c/9f3d9b68c1c6c51746e5ecdb52b2e6a2901de37e
- https://git.kernel.org/stable/c/e7632089523acddcdd8f090ad19e96fb3107b04d
- https://git.kernel.org/stable/c/e786233d2e0bbff9a82e43f02ae3a46ab4b08ec3
JSON original (NVD)
Mostrar
{
"id": "CVE-2026-72473",
"cveTags": [],
"metrics": {
"cvssMetricV31": [
{
"type": "Secondary",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"cvssData": {
"scope": "UNCHANGED",
"version": "3.1",
"baseScore": 9.8,
"attackVector": "NETWORK",
"baseSeverity": "CRITICAL",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"integrityImpact": "HIGH",
"userInteraction": "NONE",
"attackComplexity": "LOW",
"availabilityImpact": "HIGH",
"privilegesRequired": "NONE",
"confidentialityImpact": "HIGH"
},
"impactScore": 5.9,
"exploitabilityScore": 3.9
}
]
},
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "0ab115237025f5e379620bbcd56a02697d07b002",
"lessThan": "740975054a1970c0cf15f70ac39724a064f45847",
"versionType": "git"
},
{
"status": "affected",
"version": "0ab115237025f5e379620bbcd56a02697d07b002",
"lessThan": "9f3d9b68c1c6c51746e5ecdb52b2e6a2901de37e",
"versionType": "git"
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{
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"versionType": "git"
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{
"status": "affected",
"version": "0ab115237025f5e379620bbcd56a02697d07b002",
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{
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{
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"lessThan": "e786233d2e0bbff9a82e43f02ae3a46ab4b08ec3",
"versionType": "git"
}
],
"programFiles": [
"net/sunrpc/xprtrdma/backchannel.c",
"net/sunrpc/xprtrdma/rpc_rdma.c",
"net/sunrpc/xprtrdma/transport.c",
"net/sunrpc/xprtrdma/verbs.c",
"net/sunrpc/xprtrdma/xprt_rdma.h"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "5.3"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "5.3",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.1.178",
"versionType": "semver",
"lessThanOrEqual": "6.1.*"
},
{
"status": "unaffected",
"version": "6.6.145",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.97",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.40",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.1.5",
"versionType": "semver",
"lessThanOrEqual": "7.1.*"
},
{
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"net/sunrpc/xprtrdma/backchannel.c",
"net/sunrpc/xprtrdma/rpc_rdma.c",
"net/sunrpc/xprtrdma/transport.c",
"net/sunrpc/xprtrdma/verbs.c",
"net/sunrpc/xprtrdma/xprt_rdma.h"
],
"defaultStatus": "affected"
}
]
}
],
"published": "2026-08-15T06:22:21.423",
"references": [
{
"url": "https://git.kernel.org/stable/c/53442c7d0c888e51b8bc3da196970a669cc6b294",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/740975054a1970c0cf15f70ac39724a064f45847",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/8203f760a72bd39a3b66bc4eff0aa272a99fe22b",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/9f3d9b68c1c6c51746e5ecdb52b2e6a2901de37e",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/e7632089523acddcdd8f090ad19e96fb3107b04d",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/e786233d2e0bbff9a82e43f02ae3a46ab4b08ec3",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"vulnStatus": "Received",
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nxprtrdma: Decouple req recycling from RPC completion\n\nrl_kref formerly served two distinct lifetimes through a single\nrefcount: it gated when a Reply could wake its RPC task, and it\ngated when an rpcrdma_req could return to its free pool. The\nmarshal path took the Send-side reference only when SGEs needed\nDMA-unmap (sc_unmap_count > 0), which made a Send carrying only\npre-registered buffers an exception: the Reply handler dropped\nrl_kref from 1 to 0 and freed the req while the HCA might still\nbe DMA-reading from its send buffer.\n\nGive rl_kref a narrower job. The RPC layer takes one reference\nwhen slot allocation hands a req out. rpcrdma_prepare_send_sges()\ntakes a Send-side reference unconditionally after WR preparation\nsucceeds. xprt_rdma_free_slot() and xprt_rdma_bc_free_rqst() drop\nthe RPC-layer reference; rpcrdma_sendctx_unmap() drops the\nSend-side reference. The req returns to its free pool only after\nboth owners have signed off.\n\nThe existing kref_init(&req->rl_kref) call in\nrpcrdma_prepare_send_sges() is removed. Initialization moves to\nthe slot-allocation paths (xprt_rdma_alloc_slot and\nrpcrdma_bc_rqst_get), and the release callback re-arms rl_kref\nbefore the req returns to a free pool. A re-init in the marshal\npath would discard the RPC-layer reference that already exists\non entry.\n\nThree invariants follow:\n\n - Any rpcrdma_req held by an rpc_rqst has rl_kref >= 1.\n xprt_rdma_alloc_slot(), rpcrdma_bc_rqst_get(), and the\n backlog-wake branch in xprt_rdma_alloc_slot() each kref_init\n rl_kref before publishing the req. Without this invariant,\n an RPC task that aborts between slot allocation and marshal\n (gss_refresh failure or signal during call_connect, for\n example) would drive xprt_release() ->\n xprt_rdma_free_slot() -> kref_put against a refcount of\n zero, saturating refcount_t and stranding the slot.\n\n - The Send-side reference is taken only after WR prep\n succeeds. A mapping failure in rpcrdma_prepare_send_sges()\n runs rpcrdma_sendctx_cancel(), which DMA-unmaps the sendctx\n and clears sc_req without touching rl_kref. The sendctx\n ring walks in rpcrdma_sendctx_put_locked() and\n rpcrdma_sendctxs_destroy() skip entries with sc_req == NULL,\n so a burst of -EIO marshal failures cannot hold reqs off\n rb_send_bufs.\n\n - The release callback re-arms rl_kref so the next consumer\n enters with the invariant satisfied.\n\nReplies now complete the RPC directly. rpcrdma_reply_handler()\ncalls rpcrdma_complete_rqst() in place of kref_put on the\nnon-LocalInv branch. The LocalInv branch already completes the\nRPC from frwr_unmap_async() and is unaffected.\n\nBecause Send-side references can now outlive RPC completion,\nconnection teardown drains sendctx entries whose unsignaled\nSends never had a later signaled completion to walk the ring.\nrpcrdma_sendctxs_destroy() walks the active range and runs\nrpcrdma_sendctx_unmap() on each entry with a non-NULL sc_req\nbefore the request buffers are reset, and is moved ahead of\nrpcrdma_reqs_reset() in rpcrdma_xprt_disconnect() so the reqs\nare still in their pre-reset state when the Send-side refs are\nreleased.\n\nThe drain creates a teardown-ordering hazard on the backchannel\npath. With the new lifetime, releasing a bc_prealloc req from\nrpcrdma_req_release() re-adds it to bc_pa_list. The disconnect\nin xprt_rdma_destroy() runs after xprt_destroy_backchannel() has\nalready emptied bc_pa_list, so the drained reqs would otherwise\nleak. xprt_rdma_destroy() now runs xprt_rdma_bc_destroy(xprt, 0)\na second time after the disconnect to reclaim them."
}
],
"lastModified": "2026-08-17T06:19:15.273",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}