CVE-2026-89495
In the Linux kernel, the following vulnerability has been resolved:
ocfs2: bound namelen in dlm_migrate_request_handler
Patch series "ocfs2/dlm: bound peer-controlled lengths in the o2dlm".
The o2dlm receive handlers trust u8 length and count fields from the wire without bounding them, so a node in a DLM domain can corrupt or panic any other node with a malformed message. Three defects:
The other o2dlm receive handlers already reject an oversized name; the migration and recovery handlers have omitted it since the DLM was added (see the Fixes tags). Patch 1 bounds namelen; patch 2 validates lockname_len, num_locks, and the payload size. Conforming recovery and migration traffic is unaffected.
Leer descripción completaMostrar menos
o2net authenticates peers only by the DLM domain key, so any node that has joined the domain -- including a compromised or malicious member -- can send these messages. There is no local trigger; the attacker must already be a member of the cluster.
Each sink was confirmed under KASAN with an out-of-tree module mirroring it exactly -- a kmem_cache/kmalloc of the real destination size, then the same unclamped memcpy/loop: slab-out-of-bounds Write for the two writes, Read for the recovery walk, and a panic. A userspace AddressSanitizer build faults identically under -m32 and -m64. Scrubbed logs are available on request.
I reported this privately to security@kernel.org and the ocfs2 maintainers on 2026-06-20; with no response after the standard embargo period I am posting the fix publicly. I have no embargo requirement.
This patch (of 2):
A node receiving a DLM_MIGRATE_REQUEST message trusts the peer-supplied name length (migrate->namelen) without bounding it. dlm_init_mle() then copies that many bytes into the fixed DLM_LOCKID_NAME_MAX-byte mname[] array of an o2dlm_mle slab object, so a malformed message from a cluster peer overflows the slab object by up to ~215 bytes: a heap out-of-bounds write of attacker-controlled data, reachable by any node in the domain.
Reject an oversized name, the way dlm_master_request_handler() and the other o2dlm receive handlers already do; the migration handler omits the check entirely. Conforming messages are unaffected.
Detalles técnicos trazas, registros y código del informe original
- dlm_migrate_request_handler() passes migrate->namelen unchecked to
dlm_init_mle(), which memcpy()s it into the 32-byte mname[] of an
o2dlm_mle slab object: a heap out-of-bounds write of up to ~215
attacker-controlled bytes.
- dlm_mig_lockres_handler() passes mres->lockname_len unchecked to
dlm_init_lockres(), which memcpy()s it into the 32-byte o2dlm_lockname
slab object: a heap out-of-bounds write of up to ~223 bytes.
- the same handler trusts mres->num_locks without checking that the
message is large enough to hold that many entries, so
dlm_process_recovery_data() walks mres->ml[] past the kmalloc(data_len)
copy and trips a BUG_ON (an out-of-bounds read ending in a panic).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: 0.76%
- Percentil entre todas las CVEs puntuadas: 54
- Fecha de la puntuación: 4/10/2026
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 access60 %
Inferido por reglas deterministas a partir del vector CVSS y la CWE. Solo orientativo.
🛡️ 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/006c96ea488eca2ef5155ec76038e0a4dbf65f0a
- https://git.kernel.org/stable/c/2487bea2098322669f0563baff53e797486b823f
- https://git.kernel.org/stable/c/24989909d3413b44b104102caa6661b1e424ba0f
- https://git.kernel.org/stable/c/aabc5d8388e6f8826345f0073455dbcaaaa6491d
- https://git.kernel.org/stable/c/de10cd3b062a5235af754925fcf49beb5a1109d4
- https://git.kernel.org/stable/c/e1288865b8ceac0dcd1009ecba43de961f13d5bd
- https://git.kernel.org/stable/c/ea5b5609305a8437bc955a0834a530c12246d78f
- https://git.kernel.org/stable/c/f8658ee3327f73bd81c0bcd07cdeb5a8527fac98
JSON original (NVD)
Mostrar
{
"id": "CVE-2026-89495",
"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": [
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],
"programFiles": [
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],
"defaultStatus": "unaffected"
},
{
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"vendor": "Linux",
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"versions": [
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{
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{
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},
{
"status": "unaffected",
"version": "6.1.188",
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},
{
"status": "unaffected",
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{
"status": "unaffected",
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},
{
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"version": "6.18.50",
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{
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{
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"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
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],
"defaultStatus": "affected"
}
]
}
],
"published": "2026-09-11T20:19:31.493",
"references": [
{
"url": "https://git.kernel.org/stable/c/006c96ea488eca2ef5155ec76038e0a4dbf65f0a",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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{
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"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"vulnStatus": "Received",
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nocfs2: bound namelen in dlm_migrate_request_handler\n\nPatch series \"ocfs2/dlm: bound peer-controlled lengths in the o2dlm\".\n\nThe o2dlm receive handlers trust u8 length and count fields from the wire\nwithout bounding them, so a node in a DLM domain can corrupt or panic any\nother node with a malformed message. Three defects:\n\n - dlm_migrate_request_handler() passes migrate->namelen unchecked to\n dlm_init_mle(), which memcpy()s it into the 32-byte mname[] of an\n o2dlm_mle slab object: a heap out-of-bounds write of up to ~215\n attacker-controlled bytes.\n\n - dlm_mig_lockres_handler() passes mres->lockname_len unchecked to\n dlm_init_lockres(), which memcpy()s it into the 32-byte o2dlm_lockname\n slab object: a heap out-of-bounds write of up to ~223 bytes.\n\n - the same handler trusts mres->num_locks without checking that the\n message is large enough to hold that many entries, so\n dlm_process_recovery_data() walks mres->ml[] past the kmalloc(data_len)\n copy and trips a BUG_ON (an out-of-bounds read ending in a panic).\n\nThe other o2dlm receive handlers already reject an oversized name; the\nmigration and recovery handlers have omitted it since the DLM was added\n(see the Fixes tags). Patch 1 bounds namelen; patch 2 validates\nlockname_len, num_locks, and the payload size. Conforming recovery and\nmigration traffic is unaffected.\n\no2net authenticates peers only by the DLM domain key, so any node that has\njoined the domain -- including a compromised or malicious member -- can\nsend these messages. There is no local trigger; the attacker must already\nbe a member of the cluster.\n\nEach sink was confirmed under KASAN with an out-of-tree module mirroring\nit exactly -- a kmem_cache/kmalloc of the real destination size, then the\nsame unclamped memcpy/loop: slab-out-of-bounds Write for the two writes,\nRead for the recovery walk, and a panic. A userspace AddressSanitizer\nbuild faults identically under -m32 and -m64. Scrubbed logs are available\non request.\n\nI reported this privately to security@kernel.org and the ocfs2 maintainers\non 2026-06-20; with no response after the standard embargo period I am\nposting the fix publicly. I have no embargo requirement.\n\n\nThis patch (of 2):\n\nA node receiving a DLM_MIGRATE_REQUEST message trusts the peer-supplied\nname length (migrate->namelen) without bounding it. dlm_init_mle() then\ncopies that many bytes into the fixed DLM_LOCKID_NAME_MAX-byte mname[]\narray of an o2dlm_mle slab object, so a malformed message from a cluster\npeer overflows the slab object by up to ~215 bytes: a heap out-of-bounds\nwrite of attacker-controlled data, reachable by any node in the domain.\n\nReject an oversized name, the way dlm_master_request_handler() and the\nother o2dlm receive handlers already do; the migration handler omits the\ncheck entirely. Conforming messages are unaffected."
}
],
"lastModified": "2026-09-14T13:19:06.590",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}