CVE-2026-98251 (GCVE-0-2026-98251)
Vulnerability from cvelistv5 – Published: 2026-10-06 08:45 – Updated: 2026-10-07 06:49
VLAI
EPSS
VEX
Title
openvswitch: avoid reallocating confirmed conntrack labels
Summary
In the Linux kernel, the following vulnerability has been resolved:
openvswitch: avoid reallocating confirmed conntrack labels
ovs_ct_get_conn_labels() adds the labels extension when a conntrack
entry does not have one. Confirmed conntracks can be read locklessly,
so adding an extension may reallocate and free the extension block
while another CPU accesses it.
Only add the extension for unconfirmed conntracks. A confirmed
conntrack without labels now fails the caller's label operation instead
of reallocating its extension storage.
Severity
7.8 (High)
Assigner
References
8 references
Impacted products
2 products
| Vendor | Product | Version | |
|---|---|---|---|
| Linux | Linux |
Affected:
c2ac667358708d7cce64c78f58af6adf4c1e848b , < 4371d79ea74407fb992c985b1f94391e35bb8289
(git)
Affected: c2ac667358708d7cce64c78f58af6adf4c1e848b , < 7ff688aceada1160331a789385ea146f62fbddf7 (git) Affected: c2ac667358708d7cce64c78f58af6adf4c1e848b , < 05eab8dced6bf4d3009a6eeee16ddac99047dc83 (git) Affected: c2ac667358708d7cce64c78f58af6adf4c1e848b , < 579d87ec1e1e85729a6cb2c25961e58beb78640c (git) Affected: c2ac667358708d7cce64c78f58af6adf4c1e848b , < 2e6dd889c325abf23821e1459c3ffef59b7f0009 (git) Affected: c2ac667358708d7cce64c78f58af6adf4c1e848b , < d16f089bd700f45d720ce989d5495e1dc3be0cf8 (git) Affected: c2ac667358708d7cce64c78f58af6adf4c1e848b , < 8c9fcc6c33950d3db551af664d1fd3d998bfee56 (git) Affected: c2ac667358708d7cce64c78f58af6adf4c1e848b , < 3f118c8217c109fd13ca61caa301d72c483897ef (git) |
|
| Linux | Linux |
Affected:
4.3
Unaffected: 0 , < 4.3 (semver) Unaffected: 5.10.271 , ≤ 5.10.* (semver) Unaffected: 5.15.222 , ≤ 5.15.* (semver) Unaffected: 6.1.189 , ≤ 6.1.* (semver) Unaffected: 6.6.158 , ≤ 6.6.* (semver) Unaffected: 6.12.112 , ≤ 6.12.* (semver) Unaffected: 6.18.54 , ≤ 6.18.* (semver) Unaffected: 7.2.8 , ≤ 7.2.* (semver) Unaffected: 7.3-rc4 , ≤ * (original_commit_for_fix) |
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nopenvswitch: avoid reallocating confirmed conntrack labels\n\novs_ct_get_conn_labels() adds the labels extension when a conntrack\nentry does not have one. Confirmed conntracks can be read locklessly,\nso adding an extension may reallocate and free the extension block\nwhile another CPU accesses it.\n\nOnly add the extension for unconfirmed conntracks. A confirmed\nconntrack without labels now fails the caller\u0027s label operation instead\nof reallocating its extension storage."
}
],
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"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
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{
"lang": "en",
"value": "AV:L - The bad state is created by local setup over the OVS genetlink datapath/flow commands: a ct(commit,labels) action hits ovs_ct_commit()-\u003eovs_ct_set_labels()-\u003eovs_ct_get_conn_labels() on a confirmed conntrack created before labels_used was raised. Packets only trigger it; the cause is local flow and conntrack ordering.\nAC:L - The attacker creates the unlabelled confirmed conntrack (netfilter traffic before OVS init), installs the label flow, and sends both the triggering packet and the concurrent lockless ct-\u003eext readers on other CPUs, so they control both sides of the krealloc race.\nPR:L - The OVS datapath/flow genl ops use GENL_UNS_ADMIN_PERM, so CAP_NET_ADMIN in a user-owned network namespace (unshare -Urn) is enough; real root is not needed.\nUI:N - No victim action is needed; the attacker sets up the flows and sends all the packets themselves.\nS:U - The corruption is in the kernel\u0027s own conntrack extension memory and the impact stays inside the kernel\u0027s authority; no VM or hardware boundary is crossed.\nC:H - nf_ct_ext_add() on a confirmed ct does krealloc(ct-\u003eext) and frees the old extension block while other CPUs still dereference it locklessly. That is a slab use-after-free which can be reclaimed with attacker-sprayed data to leak kernel memory.\nI:H - Concurrent writers into the freed nf_ct_ext (labels, acct, ecache, helper data) write into reclaimed memory, a use-after-free write primitive that can be groomed to corrupt kernel objects.\nA:H - The use-after-free on ct-\u003eext can oops the kernel, and WARN_ON(nf_ct_is_confirmed(ct)) in nf_ct_ext_add() panics hosts with panic_on_warn set."
}
]
}
],
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"title": "openvswitch: avoid reallocating confirmed conntrack labels",
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"datePublished": "2026-10-06T08:45:18.707Z",
"dateReserved": "2026-09-25T10:25:14.331Z",
"dateUpdated": "2026-10-07T06:49:38.707Z",
"state": "PUBLISHED"
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"url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-98251.json",
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"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nopenvswitch: avoid reallocating confirmed conntrack labels\n\novs_ct_get_conn_labels() adds the labels extension when a conntrack\nentry does not have one. Confirmed conntracks can be read locklessly,\nso adding an extension may reallocate and free the extension block\nwhile another CPU accesses it.\n\nOnly add the extension for unconfirmed conntracks. A confirmed\nconntrack without labels now fails the caller\u0027s label operation instead\nof reallocating its extension storage."
}
],
"id": "CVE-2026-98251",
"lastModified": "2026-10-19T10:18:25.987",
"metrics": {
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"attackComplexity": "LOW",
"attackVector": "LOCAL",
"availabilityImpact": "HIGH",
"baseScore": 7.8,
"baseSeverity": "HIGH",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "LOW",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
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"impactScore": 5.9,
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"type": "Secondary"
}
]
},
"published": "2026-10-06T09:18:13.567",
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"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Received"
}
},
"redhat_vex": {
"aggregate_severity": "Moderate",
"current_release_date": "2026-10-10T17:32:28+00:00",
"cve": "CVE-2026-98251",
"id": "CVE-2026-98251",
"initial_release_date": "2026-10-06T00:00:00+00:00",
"product_status:known_affected": "263",
"product_status:known_not_affected": "14",
"source": "Red Hat CSAF VEX",
"status": "final",
"title": "kernel: openvswitch: avoid reallocating confirmed conntrack labels",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-98251.json",
"version": "3"
},
"suse_vex": {
"aggregate_severity": "important",
"current_release_date": "2026-10-09T16:53:35Z",
"cve": "CVE-2026-98251",
"id": "CVE-2026-98251",
"initial_release_date": "2026-10-09T16:53:35Z",
"product_status:known_affected": "343",
"product_status:known_not_affected": "4",
"source": "SUSE CSAF VEX",
"status": "interim",
"title": "SUSE CVE CVE-2026-98251",
"url": "https://ftp.suse.com/pub/projects/security/csaf-vex/2026/cve-2026-98251.json",
"version": "2"
}
}
}
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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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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.
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