CVE-2025-38721
Estado: ModificadaMedia (5.5)—
In the Linux kernel, the following vulnerability has been resolved:
netfilter: ctnetlink: fix refcount leak on table dump
While its very unlikely, its possible that ct == last. If this happens, then the refcount of ct was already incremented. This 2nd increment is never undone.
This prevents the conntrack object from being released, which in turn keeps prevents cnet->count from dropping back to 0.
This will then block the netns dismantle (or conntrack rmmod) as nf_conntrack_cleanup_net_list() will wait forever.
This can be reproduced by running conntrack_resize.sh selftest in a loop. It takes ~20 minutes for me on a preemptible kernel on average before I see a runaway kworker spinning in nf_conntrack_cleanup_net_list.
Leer descripción completaMostrar menos
But this reference counting isn't needed in the first place. We can just store a cookie value instead.
A followup patch will do the same for ctnetlink_exp_dump_table, it looks to me as if this has the same problem and like ctnetlink_dump_table, we only need a 'skip hint', not the actual object so we can apply the same cookie strategy there as well.
Detalles técnicos trazas, registros y código del informe original
There is a reference count leak in ctnetlink_dump_table():
if (res < 0) {
nf_conntrack_get(&ct->ct_general); // HERE
cb->args[1] = (unsigned long)ct;
...
One fix would to change this to:
if (res < 0) {
if (ct != last)
nf_conntrack_get(&ct->ct_general);CVSS
- Versión: 3.1
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- Puntuación base: 5.5
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.17%
- Percentil entre todas las CVEs puntuadas: 6
- Fecha de la puntuación: 6/10/2026
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).
Tecnologías afectadas (2)
CWE
- NVD-CWE-Other
Referencias
- https://git.kernel.org/stable/c/19b909a4b1452fb97e477d2f08b97f8d04095619
- https://git.kernel.org/stable/c/30cf811058552b8cd0e98dff677ef3f89d6d34ce
- https://git.kernel.org/stable/c/41462f4cfc583513833f87f9ee55d12da651a7e3
- https://git.kernel.org/stable/c/586892e341fbf698e7cbaca293e1353957db725a
- https://git.kernel.org/stable/c/962518c6ca9f9a13df099cafa429f72f68ad61f0
- https://git.kernel.org/stable/c/a2cb4df7872de069f809de2f076ec8e54d649fe3
- https://git.kernel.org/stable/c/a62d6aa3f31f216b637a4c71b7a8bfc7c57f049b
- https://git.kernel.org/stable/c/de788b2e6227462b6dcd0e07474e72c089008f74
- https://git.kernel.org/stable/c/e14f72aa66c029db106921d621edcedef68e065b
- https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html
- https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html
- https://cert-portal.siemens.com/productcert/html/ssa-019113.html
- https://cert-portal.siemens.com/productcert/html/ssa-032379.html
- https://cert-portal.siemens.com/productcert/html/ssa-082556.html
JSON original (NVD)
Mostrar
{
"id": "CVE-2025-38721",
"cveTags": [],
"metrics": {
"cvssMetricV31": [
{
"type": "Primary",
"source": "nvd@nist.gov",
"cvssData": {
"scope": "UNCHANGED",
"version": "3.1",
"baseScore": 5.5,
"attackVector": "LOCAL",
"baseSeverity": "MEDIUM",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"integrityImpact": "NONE",
"userInteraction": "NONE",
"attackComplexity": "LOW",
"availabilityImpact": "HIGH",
"privilegesRequired": "LOW",
"confidentialityImpact": "NONE"
},
"impactScore": 3.6,
"exploitabilityScore": 1.8
}
]
},
"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": "d205dc40798d97d63ad348bfaf7394f445d152d4",
"lessThan": "586892e341fbf698e7cbaca293e1353957db725a",
"versionType": "git"
},
{
"status": "affected",
"version": "d205dc40798d97d63ad348bfaf7394f445d152d4",
"lessThan": "962518c6ca9f9a13df099cafa429f72f68ad61f0",
"versionType": "git"
},
{
"status": "affected",
"version": "d205dc40798d97d63ad348bfaf7394f445d152d4",
"lessThan": "19b909a4b1452fb97e477d2f08b97f8d04095619",
"versionType": "git"
},
{
"status": "affected",
"version": "d205dc40798d97d63ad348bfaf7394f445d152d4",
"lessThan": "41462f4cfc583513833f87f9ee55d12da651a7e3",
"versionType": "git"
},
{
"status": "affected",
"version": "d205dc40798d97d63ad348bfaf7394f445d152d4",
"lessThan": "30cf811058552b8cd0e98dff677ef3f89d6d34ce",
"versionType": "git"
},
{
"status": "affected",
"version": "d205dc40798d97d63ad348bfaf7394f445d152d4",
"lessThan": "a2cb4df7872de069f809de2f076ec8e54d649fe3",
"versionType": "git"
},
{
"status": "affected",
"version": "d205dc40798d97d63ad348bfaf7394f445d152d4",
"lessThan": "e14f72aa66c029db106921d621edcedef68e065b",
"versionType": "git"
},
{
"status": "affected",
"version": "d205dc40798d97d63ad348bfaf7394f445d152d4",
"lessThan": "a62d6aa3f31f216b637a4c71b7a8bfc7c57f049b",
"versionType": "git"
},
{
"status": "affected",
"version": "d205dc40798d97d63ad348bfaf7394f445d152d4",
"lessThan": "de788b2e6227462b6dcd0e07474e72c089008f74",
"versionType": "git"
}
],
"programFiles": [
"net/netfilter/nf_conntrack_netlink.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "2.6.18"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "2.6.18",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "5.4.297",
"versionType": "semver",
"lessThanOrEqual": "5.4.*"
},
{
"status": "unaffected",
"version": "5.10.241",
"versionType": "semver",
"lessThanOrEqual": "5.10.*"
},
{
"status": "unaffected",
"version": "5.15.190",
"versionType": "semver",
"lessThanOrEqual": "5.15.*"
},
{
"status": "unaffected",
"version": "6.1.149",
"versionType": "semver",
"lessThanOrEqual": "6.1.*"
},
{
"status": "unaffected",
"version": "6.6.103",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.43",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.15.11",
"versionType": "semver",
"lessThanOrEqual": "6.15.*"
},
{
"status": "unaffected",
"version": "6.16.2",
"versionType": "semver",
"lessThanOrEqual": "6.16.*"
},
{
"status": "unaffected",
"version": "6.17",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"net/netfilter/nf_conntrack_netlink.c"
],
"defaultStatus": "affected"
}
]
},
{
"source": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e",
"affectedData": [
{
"vendor": "Siemens",
"product": "SIMATIC CN 4100",
"versions": [
{
"status": "affected",
"version": "0",
"lessThan": "V5.0",
"versionType": "custom"
}
],
"defaultStatus": "unknown"
},
{
"vendor": "Siemens",
"product": "SIMATIC S7-1500 CPU 1518-4 PN/DP MFP",
"versions": [
{
"status": "affected",
"version": "V3.1.5",
"lessThan": "*",
"versionType": "custom"
}
],
"defaultStatus": "unknown"
},
{
"vendor": "Siemens",
"product": "SIMATIC S7-1500 CPU 1518-4 PN/DP MFP",
"versions": [
{
"status": "affected",
"version": "V3.1.6",
"lessThan": "*",
"versionType": "custom"
}
],
"defaultStatus": "unknown"
},
{
"vendor": "Siemens",
"product": "SIMATIC S7-1500 CPU 1518-4 PN/DP MFP",
"versions": [
{
"status": "affected",
"version": "V3.1.5",
"lessThan": "*",
"versionType": "custom"
}
],
"defaultStatus": "unknown"
},
{
"vendor": "Siemens",
"product": "SIMATIC S7-1500 CPU 1518-4 PN/DP MFP",
"versions": [
{
"status": "affected",
"version": "V3.1.6",
"lessThan": "*",
"versionType": "custom"
}
],
"defaultStatus": "unknown"
},
{
"vendor": "Siemens",
"product": "SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP",
"versions": [
{
"status": "affected",
"version": "V3.1.5",
"lessThan": "*",
"versionType": "custom"
}
],
"defaultStatus": "unknown"
},
{
"vendor": "Siemens",
"product": "SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP",
"versions": [
{
"status": "affected",
"version": "V3.1.6",
"lessThan": "*",
"versionType": "custom"
}
],
"defaultStatus": "unknown"
},
{
"vendor": "Siemens",
"product": "SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP",
"versions": [
{
"status": "affected",
"version": "V3.1.5",
"lessThan": "*",
"versionType": "custom"
}
],
"defaultStatus": "unknown"
},
{
"vendor": "Siemens",
"product": "SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP",
"versions": [
{
"status": "affected",
"version": "V3.1.6",
"lessThan": "*",
"versionType": "custom"
}
],
"defaultStatus": "unknown"
},
{
"vendor": "Siemens",
"product": "SIPLUS S7-1500 CPU 1518-4 PN/DP MFP",
"versions": [
{
"status": "affected",
"version": "V3.1.5",
"lessThan": "*",
"versionType": "custom"
}
],
"defaultStatus": "unknown"
},
{
"vendor": "Siemens",
"product": "SIPLUS S7-1500 CPU 1518-4 PN/DP MFP",
"versions": [
{
"status": "affected",
"version": "V3.1.6",
"lessThan": "*",
"versionType": "custom"
}
],
"defaultStatus": "unknown"
}
]
}
],
"published": "2025-09-04T16:15:41.843",
"references": [
{
"url": "https://git.kernel.org/stable/c/19b909a4b1452fb97e477d2f08b97f8d04095619",
"tags": [
"Patch"
],
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/30cf811058552b8cd0e98dff677ef3f89d6d34ce",
"tags": [
"Patch"
],
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/41462f4cfc583513833f87f9ee55d12da651a7e3",
"tags": [
"Patch"
],
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/586892e341fbf698e7cbaca293e1353957db725a",
"tags": [
"Patch"
],
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/962518c6ca9f9a13df099cafa429f72f68ad61f0",
"tags": [
"Patch"
],
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/a2cb4df7872de069f809de2f076ec8e54d649fe3",
"tags": [
"Patch"
],
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/a62d6aa3f31f216b637a4c71b7a8bfc7c57f049b",
"tags": [
"Patch"
],
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/de788b2e6227462b6dcd0e07474e72c089008f74",
"tags": [
"Patch"
],
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/e14f72aa66c029db106921d621edcedef68e065b",
"tags": [
"Patch"
],
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html",
"tags": [
"Mailing List",
"Third Party Advisory"
],
"source": "af854a3a-2127-422b-91ae-364da2661108"
},
{
"url": "https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html",
"tags": [
"Mailing List",
"Third Party Advisory"
],
"source": "af854a3a-2127-422b-91ae-364da2661108"
},
{
"url": "https://cert-portal.siemens.com/productcert/html/ssa-019113.html",
"source": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"
},
{
"url": "https://cert-portal.siemens.com/productcert/html/ssa-032379.html",
"source": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"
},
{
"url": "https://cert-portal.siemens.com/productcert/html/ssa-082556.html",
"source": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"
}
],
"vulnStatus": "Modified",
"weaknesses": [
{
"type": "Primary",
"source": "nvd@nist.gov",
"description": [
{
"lang": "en",
"value": "NVD-CWE-Other"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: ctnetlink: fix refcount leak on table dump\n\nThere is a reference count leak in ctnetlink_dump_table():\n if (res < 0) {\n nf_conntrack_get(&ct->ct_general); // HERE\n cb->args[1] = (unsigned long)ct;\n ...\n\nWhile its very unlikely, its possible that ct == last.\nIf this happens, then the refcount of ct was already incremented.\nThis 2nd increment is never undone.\n\nThis prevents the conntrack object from being released, which in turn\nkeeps prevents cnet->count from dropping back to 0.\n\nThis will then block the netns dismantle (or conntrack rmmod) as\nnf_conntrack_cleanup_net_list() will wait forever.\n\nThis can be reproduced by running conntrack_resize.sh selftest in a loop.\nIt takes ~20 minutes for me on a preemptible kernel on average before\nI see a runaway kworker spinning in nf_conntrack_cleanup_net_list.\n\nOne fix would to change this to:\n if (res < 0) {\n\t\tif (ct != last)\n\t nf_conntrack_get(&ct->ct_general);\n\nBut this reference counting isn't needed in the first place.\nWe can just store a cookie value instead.\n\nA followup patch will do the same for ctnetlink_exp_dump_table,\nit looks to me as if this has the same problem and like\nctnetlink_dump_table, we only need a 'skip hint', not the actual\nobject so we can apply the same cookie strategy there as well."
}
],
"lastModified": "2026-07-14T13:17:42.863",
"configurations": [
{
"nodes": [
{
"negate": false,
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "0706A31F-1839-40E9-B535-49B47368E988",
"versionEndExcluding": "5.4.297",
"versionStartIncluding": "2.6.19"
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "D0D21C35-EB8A-488A-BBF9-403E4817E5DD",
"versionEndExcluding": "5.10.241",
"versionStartIncluding": "5.5"
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "AD9E597F-3DDE-4D7E-976C-463D0611F13F",
"versionEndExcluding": "5.15.190",
"versionStartIncluding": "5.11"
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "FDBE8280-8983-4D2D-943D-2E6D0104E2D8",
"versionEndExcluding": "6.1.149",
"versionStartIncluding": "5.16"
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "F2293654-7169-49B5-8D0D-EE51EF8B8E48",
"versionEndExcluding": "6.6.103",
"versionStartIncluding": "6.2"
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "472C5F87-2BF3-4FAB-9B21-DA7513977363",
"versionEndExcluding": "6.12.43",
"versionStartIncluding": "6.7"
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "BC242347-F722-43AE-B910-BE0B22386977",
"versionEndExcluding": "6.15.11",
"versionStartIncluding": "6.13"
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "BD7C087D-2415-4521-B624-30003352F899",
"versionEndExcluding": "6.16.2",
"versionStartIncluding": "6.16"
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:2.6.18:-:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "27C7E25A-EC60-460D-8662-016437F7C0FB"
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:2.6.18:rc5:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "F2975DF7-F916-456C-BF7C-2694559E5282"
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:2.6.18:rc6:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "6D156EFF-D2E5-4F42-B6E7-954DE6CD90B4"
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:2.6.18:rc7:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "784EB96E-2FD3-4F77-8DB6-4D6C7A928946"
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:6.17:rc1:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "327D22EF-390B-454C-BD31-2ED23C998A1C"
}
],
"operator": "OR"
}
]
},
{
"nodes": [
{
"negate": false,
"cpeMatch": [
{
"criteria": "cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "FA6FEEC2-9F11-4643-8827-749718254FED"
}
],
"operator": "OR"
}
]
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}