CVE-2026-74347
In the Linux kernel, the following vulnerability has been resolved:
netfilter: cttimeout: detach dataplane timeout policy and repurpose refcount
Add a refcount for struct nf_ct_timeout which is used by ct extension to set the custom ct timeout policy, this tells us that the ct timeout is being used by a conntrack entry. When the last conntrack entry drops the refcount on the ct timeout, the ct timeout is released.
Remove the refcount for control plane which controls if the ruleset refers to the timeout policy. After this update, it is possible to remove the ct timeout policy from nfnetlink_cttimeout immediately. This is for simplicity not to handle two refcounts on a single object.
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Remove nf_queue_nf_hook_drop(): a packet sitting in nfqueue will just hold a reference to the nf_ct_timeout object until packet is reinjected, since this is part of the ct extension, this will be released by the time the conntrack is freed.
nf_ct_untimeout() is still called to clean up in a best effort basis: the ct timeout on existing entries gets removed when the ct timeout goes away, but as long as the iptables ruleset still refers to the ct timeout through a template, new conntracks may keep attaching it and extend its lifetime until the rule is removed.
nf_ct_untimeout() is not called anymore from module removal path, this is unlikely to find timeouts give module refcount is bumped, and the new refcount already tracks the ct timeout policy use so it is released when unused.
CVSS
- Versión: 3.1
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Puntuación base: 7.8
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.18%
- 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).
🎯 Técnicas ATT&CK
Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.
- Explotación
T1068Exploitation for Privilege Escalationprivilege escalation85 % - Impacto principal
T1499.004Application or System Exploitationimpact75 %
AV:L/PR:L sin UI indica escalada local. El fallo en gestión de refcount en netfilter puede causar DoS por agotamiento de recursos en el kernel.
Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.
🛡️ 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
JSON original (NVD)
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{
"id": "CVE-2026-74347",
"cveTags": [],
"metrics": {
"cvssMetricV31": [
{
"type": "Secondary",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"cvssData": {
"scope": "UNCHANGED",
"version": "3.1",
"baseScore": 7.8,
"attackVector": "LOCAL",
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"integrityImpact": "HIGH",
"userInteraction": "NONE",
"attackComplexity": "LOW",
"availabilityImpact": "HIGH",
"privilegesRequired": "LOW",
"confidentialityImpact": "HIGH"
},
"impactScore": 5.9,
"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": "50978462300f74dc48aea4a38471cb69bdf741a5",
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],
"programFiles": [
"include/net/netfilter/nf_conntrack_timeout.h",
"net/netfilter/nf_conntrack_core.c",
"net/netfilter/nf_conntrack_timeout.c",
"net/netfilter/nfnetlink_cttimeout.c",
"net/netfilter/nft_ct.c",
"net/netfilter/xt_CT.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "3.4"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "3.4",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.12.112",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.53",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.1.5",
"versionType": "semver",
"lessThanOrEqual": "7.1.*"
},
{
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"include/net/netfilter/nf_conntrack_timeout.h",
"net/netfilter/nf_conntrack_core.c",
"net/netfilter/nf_conntrack_timeout.c",
"net/netfilter/nfnetlink_cttimeout.c",
"net/netfilter/nft_ct.c",
"net/netfilter/xt_CT.c"
],
"defaultStatus": "affected"
}
]
}
],
"published": "2026-08-15T06:22:35.860",
"references": [
{
"url": "https://git.kernel.org/stable/c/44583fd5735cb0bdf3bfe11b1e51504ce387bdb7",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/7d6a9cdb8d3a51d9cfe546a09a518ab3d2671549",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/9aeb0dcfeb460d33d61d434148b51103ab1d2013",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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{
"url": "https://git.kernel.org/stable/c/b2e84317f334d834fb06c9b340ea465f398b6d4f",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"vulnStatus": "Received",
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: cttimeout: detach dataplane timeout policy and repurpose refcount\n\nAdd a refcount for struct nf_ct_timeout which is used by ct extension to\nset the custom ct timeout policy, this tells us that the ct timeout is\nbeing used by a conntrack entry. When the last conntrack entry drops the\nrefcount on the ct timeout, the ct timeout is released.\n\nRemove the refcount for control plane which controls if the ruleset\nrefers to the timeout policy. After this update, it is possible to\nremove the ct timeout policy from nfnetlink_cttimeout immediately.\nThis is for simplicity not to handle two refcounts on a single object.\n\nRemove nf_queue_nf_hook_drop(): a packet sitting in nfqueue will just\nhold a reference to the nf_ct_timeout object until packet is reinjected,\nsince this is part of the ct extension, this will be released by the\ntime the conntrack is freed.\n\nnf_ct_untimeout() is still called to clean up in a best effort basis:\nthe ct timeout on existing entries gets removed when the ct timeout goes\naway, but as long as the iptables ruleset still refers to the ct timeout\nthrough a template, new conntracks may keep attaching it and extend its\nlifetime until the rule is removed.\n\nnf_ct_untimeout() is not called anymore from module removal path, this\nis unlikely to find timeouts give module refcount is bumped, and the new\nrefcount already tracks the ct timeout policy use so it is released when\nunused."
}
],
"lastModified": "2026-10-03T11:17:38.697",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}