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CVE-2025-40183

bpf: Fix metadata_dst leak __bpf_redirect_neigh_v{4,6}

At a glance

Severity
HIGH 7.5
EPSS
EPSS 0.62 % · percentile 50 (2026-10-28)
State
PUBLISHED
Published
Updated
Assigner
Linux
NVD status
Deferred

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.

Scores

VersionScoreVectorScored by
CVSS 3.1HIGH 7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HLinux
CVSS 3.1HIGH 7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HNVD · 416baaa9-dc9f-4396-8d5f-8c081fb06d67 (Secondary)

European references

CERT-FR advisories

Affected products

ProductVersions
Linux · Linuxaffected b4ab31414970a7a03a5d55d75083f2c101a30592 < 3fba965a9aac0fa3cbd8138436a37af9ab466d79 ; affected b4ab31414970a7a03a5d55d75083f2c101a30592 < 057764172fcc6ee2ccb6c41351a55a9f054dc8fd ; affected b4ab31414970a7a03a5d55d75083f2c101a30592 < 2e67c2037382abb56497bb9d7b7e10be04eb5598 ; affected b4ab31414970a7a03a5d55d75083f2c101a30592 < b6bfe44b6dbb14a31d86c475cdc9c7689534fb09 ; affected b4ab31414970a7a03a5d55d75083f2c101a30592 < f36a305d30f557306d87c787ddffe094ac5dac89 ; affected b4ab31414970a7a03a5d55d75083f2c101a30592 < 7404ce888a45eb7da0508b7cbbe6f2e95302eeb8
Linux · Linuxaffected 5.10 ; unaffected 0 < 5.10 ; unaffected 5.10.246 ≤ 5.10.* ; unaffected 5.15.195 ≤ 5.15.* ; unaffected 6.1.157 ≤ 6.1.* ; unaffected 6.6.113 ≤ 6.6.*

References

Sources

SourceLicence
CVE List (CVEProject cvelistV5)CVE Program Terms of Use
EPSS (FIRST.org)FIRST — attribution requested
ENISA EUVDENISA — reproduction authorised, source acknowledged
CERT-FR (ANSSI)Licence Ouverte / Etalab 2.0
NVD (NIST) via fkie-cad/nvd-json-data-feedsPublic domain — this product uses data from the NVD API but is not endorsed or certified by the NVD