ghsa-553v-hjpm-738q
Vulnerability from github
In the Linux kernel, the following vulnerability has been resolved:
bpf: Fix metadata_dst leak __bpf_redirect_neigh_v{4,6}
Cilium has a BPF egress gateway feature which forces outgoing K8s Pod traffic to pass through dedicated egress gateways which then SNAT the traffic in order to interact with stable IPs outside the cluster.
The traffic is directed to the gateway via vxlan tunnel in collect md mode. A recent BPF change utilized the bpf_redirect_neigh() helper to forward packets after the arrival and decap on vxlan, which turned out over time that the kmalloc-256 slab usage in kernel was ever-increasing.
The issue was that vxlan allocates the metadata_dst object and attaches it through a fake dst entry to the skb. The latter was never released though given bpf_redirect_neigh() was merely setting the new dst entry via skb_dst_set() without dropping an existing one first.
{
"affected": [],
"aliases": [
"CVE-2025-40183"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-11-12T22:15:45Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix metadata_dst leak __bpf_redirect_neigh_v{4,6}\n\nCilium has a BPF egress gateway feature which forces outgoing K8s Pod\ntraffic to pass through dedicated egress gateways which then SNAT the\ntraffic in order to interact with stable IPs outside the cluster.\n\nThe traffic is directed to the gateway via vxlan tunnel in collect md\nmode. A recent BPF change utilized the bpf_redirect_neigh() helper to\nforward packets after the arrival and decap on vxlan, which turned out\nover time that the kmalloc-256 slab usage in kernel was ever-increasing.\n\nThe issue was that vxlan allocates the metadata_dst object and attaches\nit through a fake dst entry to the skb. The latter was never released\nthough given bpf_redirect_neigh() was merely setting the new dst entry\nvia skb_dst_set() without dropping an existing one first.",
"id": "GHSA-553v-hjpm-738q",
"modified": "2025-11-13T00:30:17Z",
"published": "2025-11-13T00:30:17Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-40183"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/057764172fcc6ee2ccb6c41351a55a9f054dc8fd"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/23f3770e1a53e6c7a553135011f547209e141e72"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/2e67c2037382abb56497bb9d7b7e10be04eb5598"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/3fba965a9aac0fa3cbd8138436a37af9ab466d79"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/7404ce888a45eb7da0508b7cbbe6f2e95302eeb8"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/b6bfe44b6dbb14a31d86c475cdc9c7689534fb09"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f36a305d30f557306d87c787ddffe094ac5dac89"
}
],
"schema_version": "1.4.0",
"severity": []
}
Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
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- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.