CVE-2026-74625 (GCVE-0-2026-74625)
Vulnerability from cvelistv5
Published
2026-08-22 15:32
Modified
2026-08-25 05:40
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
netfilter: bridge: release template ct on non-IP path
A bridge nftables ct zone set rule can attach a conntrack template to
an skb before nf_ct_bridge_pre() sees it. For non-IPv4 and non-IPv6
EtherTypes, nf_ct_bridge_pre() currently overwrites skb->_nfct with
IP_CT_UNTRACKED without releasing the existing template reference.
That makes the per-cpu template, and any temporary templates allocated
for concurrent use, unreachable and leaks memory until the host runs out
of slab.
Reset the skb conntrack state before marking the frame untracked so the
existing template reference is dropped on the non-IP path.
References
Impacted products
| Vendor | Product | Version | ||
|---|---|---|---|---|
| Linux | Linux |
Version: 3c171f496ef57774f8e5d509923372549734877f Version: 3c171f496ef57774f8e5d509923372549734877f Version: 3c171f496ef57774f8e5d509923372549734877f Version: 3c171f496ef57774f8e5d509923372549734877f Version: 3c171f496ef57774f8e5d509923372549734877f Version: 3c171f496ef57774f8e5d509923372549734877f Version: 3c171f496ef57774f8e5d509923372549734877f Version: 3c171f496ef57774f8e5d509923372549734877f |
||
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"net/bridge/netfilter/nf_conntrack_bridge.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "fc90df37540627d092af770215fb4b7befe9409b",
"status": "affected",
"version": "3c171f496ef57774f8e5d509923372549734877f",
"versionType": "git"
},
{
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"status": "affected",
"version": "3c171f496ef57774f8e5d509923372549734877f",
"versionType": "git"
},
{
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"status": "affected",
"version": "3c171f496ef57774f8e5d509923372549734877f",
"versionType": "git"
},
{
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"status": "affected",
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},
{
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{
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"versionType": "git"
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{
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"status": "affected",
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{
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"status": "affected",
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}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"net/bridge/netfilter/nf_conntrack_bridge.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "5.3"
},
{
"lessThan": "5.3",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.10.*",
"status": "unaffected",
"version": "5.10.265",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.15.*",
"status": "unaffected",
"version": "5.15.216",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"version": "6.1.183",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"version": "6.6.152",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.104",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.45",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.1.*",
"status": "unaffected",
"version": "7.1.9",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "5.10.265",
"versionStartIncluding": "5.3",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "5.15.216",
"versionStartIncluding": "5.3",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.1.183",
"versionStartIncluding": "5.3",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.6.152",
"versionStartIncluding": "5.3",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.12.104",
"versionStartIncluding": "5.3",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.18.45",
"versionStartIncluding": "5.3",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.1.9",
"versionStartIncluding": "5.3",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.2",
"versionStartIncluding": "5.3",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: bridge: release template ct on non-IP path\n\nA bridge nftables ct zone set rule can attach a conntrack template to\nan skb before nf_ct_bridge_pre() sees it. For non-IPv4 and non-IPv6\nEtherTypes, nf_ct_bridge_pre() currently overwrites skb-\u003e_nfct with\nIP_CT_UNTRACKED without releasing the existing template reference.\n\nThat makes the per-cpu template, and any temporary templates allocated\nfor concurrent use, unreachable and leaks memory until the host runs out\nof slab.\n\nReset the skb conntrack state before marking the frame untracked so the\nexisting template reference is dropped on the non-IP path."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 7.5,
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"version": "3.1"
},
"scenarios": [
{
"lang": "en",
"value": "AV:N - Non-IP L2 frames (ARP/LLDP) injected into a Linux bridge reach NF_BR_PRE_ROUTING via br_handle_frame\u2192nf_hook_bridge_pre; on overlay/container hosts (VXLAN/GRE bridges in Docker/k8s/OpenStack) remote peers can deliver those frames across routed networks to the victim bridge port.\nAC:L - Once a bridge nftables ct zone set rule runs before NF_IP_PRI_CONNTRACK (-200), every non-IPv4/IPv6 EtherType frame deterministically leaks template references; the attacker controls rule priority, zone value, and can flood ARP/LLDP to accelerate the leak without races.\nPR:N - On bridge firewalls/routers with deployed nftables ct zone marking, exploitation needs only unauthenticated L2 packet delivery\u2014no host UID, capability, or namespace privilege; CAP_NET_ADMIN (obtainable via user namespaces) is an alternate Low path for self-setup but not required on pre-configured appliances.\nUI:N - Bridge netfilter processes received frames automatically in softirq; no victim mount, click, or administrative action is required beyond normal bridge forwarding of attacker-supplied non-IP traffic.\nS:U - Impact is unbounded kernel slab consumption from leaked nf_conn template objects within the host kernel; it does not cross VM, container, IOMMU, or hypervisor security boundaries.\nC:N - The bug is a missing nf_conntrack_put()\u2014a reference-count leak\u2014not a use-after-free, out-of-bounds read, or disclosure primitive; orphaned templates are unreachable and their contents are never returned to the attacker.\nI:N - Only template reference counts are leaked via skb-\u003e_nfct overwrite; no heap corruption, type confusion, or attacker-controlled writes occur, so integrity cannot be compromised beyond availability loss from memory pressure.\nA:H - Each leaked per-CPU and temporary conntrack template is never freed; sustained non-IP frame flooding can exhaust kernel slab until OOM, causing severe host unavailability or panic on memory-allocation failure paths."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-25T05:40:48.341Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/fc90df37540627d092af770215fb4b7befe9409b"
},
{
"url": "https://git.kernel.org/stable/c/daa6e070f8e1e7a4dddec8b64ca37663f8cda917"
},
{
"url": "https://git.kernel.org/stable/c/bd7b16494dacf87e9336a1dcfdada83b9e40edd6"
},
{
"url": "https://git.kernel.org/stable/c/6ea88401e10e04e0b3bb7a7adea54932fb60b93b"
},
{
"url": "https://git.kernel.org/stable/c/46d559f00b1ab1d114f92d2f16c5ef0093b3b9dd"
},
{
"url": "https://git.kernel.org/stable/c/c58d34fe8b7e47bb0b350a7625023b1261342be5"
},
{
"url": "https://git.kernel.org/stable/c/7cff440d702616022769f2643168d7f9820547a0"
},
{
"url": "https://git.kernel.org/stable/c/d45cc8020d7c0a9f01dee42ff5c40bc14c9af72f"
}
],
"title": "netfilter: bridge: release template ct on non-IP path",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-74625",
"datePublished": "2026-08-22T15:32:07.929Z",
"dateReserved": "2026-08-15T05:44:03.921Z",
"dateUpdated": "2026-08-25T05:40:48.341Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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