CVE-2026-72222 (GCVE-0-2026-72222)
Vulnerability from cvelistv5 – Published: 2026-08-15 05:54 – Updated: 2026-08-17 05:41
VLAI
EPSS
VEX
Title
sunrpc: pin svc_xprt across the asynchronous TLS handshake callback
Summary
In the Linux kernel, the following vulnerability has been resolved:
sunrpc: pin svc_xprt across the asynchronous TLS handshake callback
svc_tcp_handshake() stores the raw svc_xprt pointer in
tls_handshake_args.ta_data and submits the request through
tls_server_hello_x509(). The handshake core takes only
sock_hold(req->hr_sk); nothing references the embedding struct
svc_sock that svc_tcp_handshake_done() reaches via container_of().
Two close races leave the in-flight callback writing through a freed
svc_sock. svc_sock_free() calls tls_handshake_cancel() and discards
its return value: a false return means handshake_complete() has
already set HANDSHAKE_F_REQ_COMPLETED but hp_done() may not have
finished, yet svc_sock_free() proceeds to kfree(svsk). The
cancel-loser fall-through inside svc_tcp_handshake() itself produces
the same window: when wait_for_completion_interruptible_timeout()
returns <= 0 (timeout or signal) and tls_handshake_cancel() returns
false, the function does not drain, returns, and svc_handle_xprt()
calls svc_xprt_received(), which clears XPT_BUSY and can drop the
last reference. A concurrent close then runs svc_sock_free() while
svc_tcp_handshake_done() is still updating xpt_flags and walking
svsk->sk_handshake_done.
The corruption surfaces as set_bit/clear_bit RMW into the freed
xpt_flags slab slot and as complete_all() walking and writing the
freed wait_queue_head_t list embedded in sk_handshake_done -- a
slab-corruption primitive, not a benign read. The path is reachable
on any TLS-enabled NFS server whenever a connection close overlaps
the tlshd downcall delivery window; the interruptible wait means
signal delivery suffices, not just SVC_HANDSHAKE_TO expiry.
Take svc_xprt_get(xprt) immediately before tls_server_hello_x509()
so the in-flight callback owns its own reference. Release it on the
two edges where the callback is guaranteed not to fire -- submission
failure from tls_server_hello_x509() and a successful
tls_handshake_cancel() -- and at the tail of
svc_tcp_handshake_done() after complete_all().
[cel: rewrote commit message to describe the actual change]
Severity
9.8 (Critical)
Assigner
References
Impacted products
2 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Linux | Linux |
Affected:
b3cbf98e2fdf3cb147a95161560cd25987284330 , < f3b55945dd99f29d83e1965d0141040a35262346
(git)
Affected: b3cbf98e2fdf3cb147a95161560cd25987284330 , < 2d4f97d13fff91e0bc539216be88b884b544d49f (git) Affected: b3cbf98e2fdf3cb147a95161560cd25987284330 , < 3f9ee75a97a769be258784c22b89657acb5ed9bd (git) Affected: b3cbf98e2fdf3cb147a95161560cd25987284330 , < 083e9c2ec7e8bb13b79c9fd7b337abdd758ecc5f (git) Affected: b3cbf98e2fdf3cb147a95161560cd25987284330 , < 4f988f3a2808fb659f3880c282041ff067acad78 (git) |
guessed | |
| Linux | Linux |
Affected:
6.4
Unaffected: 0 , < 6.4 (semver) Unaffected: 6.6.145 , ≤ 6.6.* (semver) Unaffected: 6.12.97 , ≤ 6.12.* (semver) Unaffected: 6.18.40 , ≤ 6.18.* (semver) Unaffected: 7.1.5 , ≤ 7.1.* (semver) Unaffected: 7.2 , ≤ * (original_commit_for_fix) |
guessed |
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"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsunrpc: pin svc_xprt across the asynchronous TLS handshake callback\n\nsvc_tcp_handshake() stores the raw svc_xprt pointer in\ntls_handshake_args.ta_data and submits the request through\ntls_server_hello_x509(). The handshake core takes only\nsock_hold(req-\u003ehr_sk); nothing references the embedding struct\nsvc_sock that svc_tcp_handshake_done() reaches via container_of().\n\nTwo close races leave the in-flight callback writing through a freed\nsvc_sock. svc_sock_free() calls tls_handshake_cancel() and discards\nits return value: a false return means handshake_complete() has\nalready set HANDSHAKE_F_REQ_COMPLETED but hp_done() may not have\nfinished, yet svc_sock_free() proceeds to kfree(svsk). The\ncancel-loser fall-through inside svc_tcp_handshake() itself produces\nthe same window: when wait_for_completion_interruptible_timeout()\nreturns \u003c= 0 (timeout or signal) and tls_handshake_cancel() returns\nfalse, the function does not drain, returns, and svc_handle_xprt()\ncalls svc_xprt_received(), which clears XPT_BUSY and can drop the\nlast reference. A concurrent close then runs svc_sock_free() while\nsvc_tcp_handshake_done() is still updating xpt_flags and walking\nsvsk-\u003esk_handshake_done.\n\nThe corruption surfaces as set_bit/clear_bit RMW into the freed\nxpt_flags slab slot and as complete_all() walking and writing the\nfreed wait_queue_head_t list embedded in sk_handshake_done -- a\nslab-corruption primitive, not a benign read. The path is reachable\non any TLS-enabled NFS server whenever a connection close overlaps\nthe tlshd downcall delivery window; the interruptible wait means\nsignal delivery suffices, not just SVC_HANDSHAKE_TO expiry.\n\nTake svc_xprt_get(xprt) immediately before tls_server_hello_x509()\nso the in-flight callback owns its own reference. Release it on the\ntwo edges where the callback is guaranteed not to fire -- submission\nfailure from tls_server_hello_x509() and a successful\ntls_handshake_cancel() -- and at the tail of\nsvc_tcp_handshake_done() after complete_all().\n\n[cel: rewrote commit message to describe the actual change]"
}
],
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"baseSeverity": "CRITICAL",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"scenarios": [
{
"lang": "en",
"value": "AV:N - The flaw is in nfsd\u0027s server-side SUNRPC/TCP TLS handshake (net/sunrpc/svcsock.c), reached when a remote peer connects to port 2049 and sends a pre-authentication AUTH_TLS NULL STARTTLS probe that triggers svc_tcp_handshake() via svcauth_tls_accept().\nAC:L - The attacker controls both sides of the race by initiating AUTH_TLS handshakes and concurrently resetting/closing TCP or waiting for SVC_HANDSHAKE_TO while tlshd delivers completion; repeated parallel connections make the overlap window reliably reachable.\nPR:N - AUTH_TLS is processed on RPC procedure 0 before credentials are verified, so an unauthenticated remote client can reach svc_tcp_handshake() and the asynchronous callback without any account, export access, or kernel capability.\nUI:N - nfsd worker threads automatically accept the TCP connection, process the STARTTLS probe, run the TLS handshake, and handle teardown/completion callbacks without any local user or administrator action.\nS:U - Exploitation corrupts kernel memory on the NFS server host itself and does not cross a VM-guest/host, sandbox, or IOMMU security boundary; impact stays within the kernel\u0027s security authority.\nC:H - svc_tcp_handshake_done() use-after-frees svc_sock and performs set_bit/clear_bit RMW on freed xpt_flags plus complete_all() on freed sk_handshake_done, a slab-corruption UAF that can disclose arbitrary kernel memory.\nI:H - The same UAF delivers attacker-timed writes into reclaimed slab slots through atomic bit operations and wait-queue list updates, enabling heap grooming and further kernel memory corruption for arbitrary modification or code execution.\nA:H - Slab corruption and UAF during handshake completion can cause kernel oops/panic, and unauthenticated remote peers can trigger the fault repeatedly by overlapping TLS handshake completion with connection close."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-17T05:41:44.196Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
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{
"url": "https://git.kernel.org/stable/c/4f988f3a2808fb659f3880c282041ff067acad78"
}
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"title": "sunrpc: pin svc_xprt across the asynchronous TLS handshake callback",
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"assignerShortName": "Linux",
"cveId": "CVE-2026-72222",
"datePublished": "2026-08-15T05:54:15.277Z",
"dateReserved": "2026-08-09T03:40:39.913Z",
"dateUpdated": "2026-08-17T05:41:44.196Z",
"state": "PUBLISHED"
},
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"cve": "CVE-2026-72222",
"date": "2026-10-01",
"epss": "0.00635",
"percentile": "0.48516"
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"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsunrpc: pin svc_xprt across the asynchronous TLS handshake callback\n\nsvc_tcp_handshake() stores the raw svc_xprt pointer in\ntls_handshake_args.ta_data and submits the request through\ntls_server_hello_x509(). The handshake core takes only\nsock_hold(req-\u003ehr_sk); nothing references the embedding struct\nsvc_sock that svc_tcp_handshake_done() reaches via container_of().\n\nTwo close races leave the in-flight callback writing through a freed\nsvc_sock. svc_sock_free() calls tls_handshake_cancel() and discards\nits return value: a false return means handshake_complete() has\nalready set HANDSHAKE_F_REQ_COMPLETED but hp_done() may not have\nfinished, yet svc_sock_free() proceeds to kfree(svsk). The\ncancel-loser fall-through inside svc_tcp_handshake() itself produces\nthe same window: when wait_for_completion_interruptible_timeout()\nreturns \u003c= 0 (timeout or signal) and tls_handshake_cancel() returns\nfalse, the function does not drain, returns, and svc_handle_xprt()\ncalls svc_xprt_received(), which clears XPT_BUSY and can drop the\nlast reference. A concurrent close then runs svc_sock_free() while\nsvc_tcp_handshake_done() is still updating xpt_flags and walking\nsvsk-\u003esk_handshake_done.\n\nThe corruption surfaces as set_bit/clear_bit RMW into the freed\nxpt_flags slab slot and as complete_all() walking and writing the\nfreed wait_queue_head_t list embedded in sk_handshake_done -- a\nslab-corruption primitive, not a benign read. The path is reachable\non any TLS-enabled NFS server whenever a connection close overlaps\nthe tlshd downcall delivery window; the interruptible wait means\nsignal delivery suffices, not just SVC_HANDSHAKE_TO expiry.\n\nTake svc_xprt_get(xprt) immediately before tls_server_hello_x509()\nso the in-flight callback owns its own reference. Release it on the\ntwo edges where the callback is guaranteed not to fire -- submission\nfailure from tls_server_hello_x509() and a successful\ntls_handshake_cancel() -- and at the tail of\nsvc_tcp_handshake_done() after complete_all().\n\n[cel: rewrote commit message to describe the actual change]"
}
],
"id": "CVE-2026-72222",
"lastModified": "2026-08-17T06:18:23.293",
"metrics": {
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"attackComplexity": "LOW",
"attackVector": "NETWORK",
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"baseScore": 9.8,
"baseSeverity": "CRITICAL",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
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"published": "2026-08-15T06:21:41.120",
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],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Received"
}
},
"redhat_vex": {
"aggregate_severity": "Important",
"current_release_date": "2026-08-18T16:27:52+00:00",
"cve": "CVE-2026-72222",
"id": "CVE-2026-72222",
"initial_release_date": "2026-08-15T00:00:00+00:00",
"product_status:known_affected": "184",
"product_status:known_not_affected": "76",
"product_status:under_investigation": "14",
"source": "Red Hat CSAF VEX",
"status": "final",
"title": "kernel: sunrpc: pin svc_xprt across the asynchronous TLS handshake callback",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-72222.json",
"version": "3"
},
"suse_vex": {
"aggregate_severity": "important",
"current_release_date": "2026-09-28T23:49:38Z",
"cve": "CVE-2026-72222",
"id": "CVE-2026-72222",
"initial_release_date": "2026-08-21T00:42:20Z",
"product_status:first_fixed": "68",
"product_status:known_affected": "438",
"product_status:known_not_affected": "239",
"product_status:recommended": "214",
"source": "SUSE CSAF VEX",
"status": "interim",
"title": "SUSE CVE CVE-2026-72222",
"url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-72222.json",
"version": "11"
}
}
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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