CVE-2025-40183 Affecting kernel-rt-modules package, versions *


Severity

Recommended
low

Based on CentOS security rating.

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  • Snyk IDSNYK-CENTOS8-KERNELRTMODULES-13955672
  • published14 Nov 2025
  • disclosed12 Nov 2025

Introduced: 12 Nov 2025

NewCVE-2025-40183  (opens in a new tab)

How to fix?

There is no fixed version for Centos:8 kernel-rt-modules.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-rt-modules package and not the kernel-rt-modules package as distributed by Centos. See How to fix? for Centos:8 relevant fixed versions and status.

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.

CVSS Base Scores

version 3.1