CVE-2026-63971 (GCVE-0-2026-63971)
Vulnerability from cvelistv5 – Published: 2026-07-19 14:55 – Updated: 2026-10-19 20:17
VLAI
EPSS
VEX
Title
sctp: fix race between sctp_wait_for_connect and peeloff
Summary
In the Linux kernel, the following vulnerability has been resolved:
sctp: fix race between sctp_wait_for_connect and peeloff
sctp_wait_for_connect() drops and re-acquires the socket lock while
waiting for the association to reach ESTABLISHED state. During this
window, another thread can peeloff the association to a new socket via
getsockopt(SCTP_SOCKOPT_PEELOFF), changing asoc->base.sk. After
re-acquiring the old socket lock, sctp_wait_for_connect() returns
success without noticing the migration — the caller then accesses
the association under the wrong lock in sctp_datamsg_from_user().
Add the same sk != asoc->base.sk check that sctp_wait_for_sndbuf()
already has, returning an error if the association was migrated while
we slept.
Severity
7.8 (High)
SSVC
Exploitation: none
Automatable: no
Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-10-16 15:34 UTC
CWE
- CWE-362 - Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
Assigner
References
8 references
Impacted products
2 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Linux | Linux |
Affected:
668c9beb9020d5834ee9e43c208190a07d2b1928 , < 0e0d5bc76fd4267a71334fcc8f1a5fbcf997845d
(git)
Affected: 668c9beb9020d5834ee9e43c208190a07d2b1928 , < bcfeac79af740735ace44008b4a11b8e5add20f5 (git) Affected: 668c9beb9020d5834ee9e43c208190a07d2b1928 , < 8e9b56051d24540cfbf39194618708c4a7633549 (git) Affected: 668c9beb9020d5834ee9e43c208190a07d2b1928 , < 634a9af8a26a84d8b0d7b3b643204b344b42d9fb (git) Affected: 668c9beb9020d5834ee9e43c208190a07d2b1928 , < 7d2038d4b80166f7bead8d07eba3b97405816c21 (git) Affected: 668c9beb9020d5834ee9e43c208190a07d2b1928 , < 68667ee4c7dadf7f63167234e2a1af09b3f7874e (git) Affected: 668c9beb9020d5834ee9e43c208190a07d2b1928 , < 6140cfa721451fa6e18e134e709703c2bf34d0fb (git) Affected: 668c9beb9020d5834ee9e43c208190a07d2b1928 , < f14fe6395a8b3d961a61e138ad7b36ba3626dd4e (git) |
guessed | |
| Linux | Linux |
Affected:
4.16
Unaffected: 0 , < 4.16 (semver) Unaffected: 5.10.259 , ≤ 5.10.* (semver) Unaffected: 5.15.210 , ≤ 5.15.* (semver) Unaffected: 6.1.176 , ≤ 6.1.* (semver) Unaffected: 6.6.143 , ≤ 6.6.* (semver) Unaffected: 6.12.93 , ≤ 6.12.* (semver) Unaffected: 6.18.35 , ≤ 6.18.* (semver) Unaffected: 7.0.12 , ≤ 7.0.* (semver) Unaffected: 7.1 , ≤ * (original_commit_for_fix) |
guessed |
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}
],
"id": "CVE-2026-63971",
"lastModified": "2026-10-19T21:17:14.660",
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}
],
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"type": "Secondary"
}
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}
},
"redhat_vex": {
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"current_release_date": "2026-10-19T23:40:38+00:00",
"cve": "CVE-2026-63971",
"id": "CVE-2026-63971",
"initial_release_date": "2026-07-19T00:00:00+00:00",
"product_status:fixed": "773",
"product_status:known_affected": "36",
"product_status:known_not_affected": "28",
"source": "Red Hat CSAF VEX",
"status": "final",
"title": "kernel: sctp: fix race between sctp_wait_for_connect and peeloff",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-63971.json",
"version": "3"
},
"vulnrichment": {
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{
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"options": [
{
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},
{
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}
],
"role": "CISA Coordinator",
"timestamp": "2026-10-16T15:34:18.318567Z",
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"providerMetadata": {
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"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
},
"title": "CISA ADP Vulnrichment"
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],
"cna": {
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{
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}
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"value": "AV:L - Exploitation requires local syscalls on an SCTP socket (`sendmsg`/`sendto` to trigger `sctp_wait_for_connect`, and `getsockopt(SCTP_SOCKOPT_PEELOFF)` to peel off the association). A remote peer can only help complete the SCTP handshake; it cannot invoke peeloff or the racing send path.\nAC:L - The attacker controls both sides of the race by running concurrent threads on the same SCTP one-to-many socket, timing peeloff during the window where `sctp_wait_for_connect()` has released the socket lock. Required options (`SCTP_FRAGMENT_INTERLEAVE`, `SCTP_INTERLEAVING_SUPPORTED`, and `net.sctp.intl_enable`) are attacker-settable in a user/net namespace.\nPR:L - No real-root capability is required; an unprivileged user can create SCTP sockets and drive the full race from a user namespace (`unshare -Urn`), including enabling `net.sctp.intl_enable` and the interleaving socket options needed to reach the vulnerable `sctp_sendmsg_to_asoc()` path.\nUI:N - Exploitation is fully attacker-driven through coordinated local threads and does not require any action from a victim user or administrator beyond normal SCTP socket use.\nS:U - Impact is confined to kernel memory integrity/availability within the same security authority; successful exploitation would be local privilege escalation, not a cross-boundary escape such as VM or container breakout by itself.\nC:H - After peeloff migrates `asoc-\u003ebase.sk`, the caller continues in `sctp_datamsg_from_user()` while holding the wrong socket lock, creating unsynchronized concurrent access to association/stream state that can corrupt kernel heap metadata and be leveraged for arbitrary kernel memory disclosure.\nI:H - The post-race path builds and queues DATA/I-DATA chunks via `sctp_datamsg_from_user()` and `sctp_primitive_SEND()` without the correct socket lock, enabling concurrent modification of association output queues and stream structures that can be turned into arbitrary kernel writes or control-flow hijacking.\nA:H - Concurrent unsynchronized access to a live SCTP association after peeloff can cause kernel oops/panic or wedged associations, and the underlying race is a classic kernel concurrency defect with high availability impact even before full exploitation."
}
]
}
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}
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Drag nodes to arrange them. Double-click a related vulnerability to open it, or a source to visit its link. The Physics button on the left tunes the layout and the simulation; the legend at the bottom left hides or shows nodes by kind and by sighting type.
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.
Vulnerability timeline
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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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Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.