bpf: Fix metadata_dst leak __bpf_redirect_neigh_v{4,6}

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2025-40183
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2025-11-12 22:15:45 UTC
Updated2026-07-30 06:24:16 UTC
DescriptionIn 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.

Risk And Classification

Primary CVSS: v3.1 7.5 HIGH from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS: 0.005730000 probability, percentile 0.441140000 (date 2026-07-31)

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
3.1CNADECLARED7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected b4ab31414970a7a03a5d55d75083f2c101a30592 3fba965a9aac0fa3cbd8138436a37af9ab466d79 git Not specified
CNA Linux Linux affected b4ab31414970a7a03a5d55d75083f2c101a30592 057764172fcc6ee2ccb6c41351a55a9f054dc8fd git Not specified
CNA Linux Linux affected b4ab31414970a7a03a5d55d75083f2c101a30592 2e67c2037382abb56497bb9d7b7e10be04eb5598 git Not specified
CNA Linux Linux affected b4ab31414970a7a03a5d55d75083f2c101a30592 b6bfe44b6dbb14a31d86c475cdc9c7689534fb09 git Not specified
CNA Linux Linux affected b4ab31414970a7a03a5d55d75083f2c101a30592 f36a305d30f557306d87c787ddffe094ac5dac89 git Not specified
CNA Linux Linux affected b4ab31414970a7a03a5d55d75083f2c101a30592 7404ce888a45eb7da0508b7cbbe6f2e95302eeb8 git Not specified
CNA Linux Linux affected b4ab31414970a7a03a5d55d75083f2c101a30592 23f3770e1a53e6c7a553135011f547209e141e72 git Not specified
CNA Linux Linux affected 5.10 Not specified
CNA Linux Linux unaffected 5.10 semver Not specified
CNA Linux Linux unaffected 5.10.246 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.195 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.157 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.113 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.54 6.12.* semver Not specified
CNA Linux Linux unaffected 6.17.4 6.17.* semver Not specified
CNA Linux Linux unaffected 6.18 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/23f3770e1a53e6c7a553135011f547209e141e72 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/b6bfe44b6dbb14a31d86c475cdc9c7689534fb09 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/3fba965a9aac0fa3cbd8138436a37af9ab466d79 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/f36a305d30f557306d87c787ddffe094ac5dac89 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/7404ce888a45eb7da0508b7cbbe6f2e95302eeb8 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/2e67c2037382abb56497bb9d7b7e10be04eb5598 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/057764172fcc6ee2ccb6c41351a55a9f054dc8fd 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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