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CVE-2025-40183

Full vulnerability record from the local CVENow database.

Description

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.

Severity
HIGH
CVSS score
7.5 (v3.1)
Vulnerability status
Deferred
Source identifier
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Published
2025-11-12 22:15:45.080000
Last modified
2026-10-19 21:10:00.160000
View original CVE JSON 
{
  "id": "CVE-2025-40183",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "published": "2025-11-12T22:15:45.080",
  "lastModified": "2026-10-19T21:10:00.160",
  "vulnStatus": "Deferred",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "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."
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nbpf: Corrección de fuga de metadata_dst __bpf_redirect_neigh_v{4,6}\n\nCilium tiene una característica de puerta de enlace de salida BPF que fuerza el tráfico saliente de los Pods de K8s a pasar a través de puertas de enlace de salida dedicadas que luego realizan SNAT al tráfico para interactuar con IPs estables fuera del clúster.\n\nEl tráfico se dirige a la puerta de enlace a través de un túnel vxlan en modo collect md. Un cambio reciente en BPF utilizó el ayudante bpf_redirect_neigh() para reenviar paquetes después de la llegada y desencapsulación en vxlan, lo que con el tiempo reveló que el uso de slab kmalloc-256 en el kernel estaba en constante aumento.\n\nEl problema era que vxlan asigna el objeto metadata_dst y lo adjunta a través de una entrada dst falsa al skb. Sin embargo, este último nunca se liberó, dado que bpf_redirect_neigh() simplemente estaba configurando la nueva entrada dst a través de skb_dst_set() sin eliminar primero una existente."
    }
  ],
  "affected": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "affectedData": [
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "unaffected",
          "programFiles": [
            "net/core/filter.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "versions": [
            {
              "version": "b4ab31414970a7a03a5d55d75083f2c101a30592",
              "lessThan": "3fba965a9aac0fa3cbd8138436a37af9ab466d79",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "b4ab31414970a7a03a5d55d75083f2c101a30592",
              "lessThan": "057764172fcc6ee2ccb6c41351a55a9f054dc8fd",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "b4ab31414970a7a03a5d55d75083f2c101a30592",
              "lessThan": "2e67c2037382abb56497bb9d7b7e10be04eb5598",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "b4ab31414970a7a03a5d55d75083f2c101a30592",
              "lessThan": "b6bfe44b6dbb14a31d86c475cdc9c7689534fb09",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "b4ab31414970a7a03a5d55d75083f2c101a30592",
              "lessThan": "f36a305d30f557306d87c787ddffe094ac5dac89",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "b4ab31414970a7a03a5d55d75083f2c101a30592",
              "lessThan": "7404ce888a45eb7da0508b7cbbe6f2e95302eeb8",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "b4ab31414970a7a03a5d55d75083f2c101a30592",
              "lessThan": "23f3770e1a53e6c7a553135011f547209e141e72",
              "versionType": "git",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "affected",
          "programFiles": [
            "net/core/filter.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "versions": [
            {
              "version": "5.10",
              "status": "affected"
            },
            {
              "version": "0",
              "lessThan": "5.10",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "5.10.246",
              "lessThanOrEqual": "5.10.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "5.15.195",
              "lessThanOrEqual": "5.15.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.1.157",
              "lessThanOrEqual": "6.1.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.6.113",
              "lessThanOrEqual": "6.6.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.12.54",
              "lessThanOrEqual": "6.12.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.17.4",
              "lessThanOrEqual": "6.17.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.18",
              "lessThanOrEqual": "*",
              "versionType": "original_commit_for_fix",
              "status": "unaffected"
            }
          ]
        }
      ]
    }
  ],
  "metrics": {
    "cvssMetricV31": [
      {
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary",
        "cvssData": {
          "version": "3.1",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
          "baseScore": 7.5,
          "baseSeverity": "HIGH",
          "attackVector": "NETWORK",
          "attackComplexity": "LOW",
          "privilegesRequired": "NONE",
          "userInteraction": "NONE",
          "scope": "UNCHANGED",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "availabilityImpact": "HIGH"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 3.6
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "timestamp": "2026-10-15T21:57:43.679518Z",
          "id": "CVE-2025-40183",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "version": "2.0.3"
        }
      }
    ]
  },
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/057764172fcc6ee2ccb6c41351a55a9f054dc8fd",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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      "url": "https://git.kernel.org/stable/c/3fba965a9aac0fa3cbd8138436a37af9ab466d79",
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    {
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    {
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      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
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}