CVE-2025-40183
bpf: Fix metadata_dst leak __bpf_redirect_neigh_v{4,6}
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.
INFO
Published Date :
Nov. 12, 2025, 10:15 p.m.
Last Modified :
Nov. 12, 2025, 10:15 p.m.
Remotely Exploit :
No
Source :
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Affected Products
The following products are affected by CVE-2025-40183
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
Solution
- Update the Linux kernel.
- Apply patches for bpf_redirect_neigh.
- Release existing destination entries before setting new ones.
- Monitor kmalloc-256 slab usage.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2025-40183.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2025-40183 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2025-40183
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2025-40183 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2025-40183 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Nov. 12, 2025
Action Type Old Value New Value Added 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. Added Reference https://git.kernel.org/stable/c/057764172fcc6ee2ccb6c41351a55a9f054dc8fd Added Reference https://git.kernel.org/stable/c/23f3770e1a53e6c7a553135011f547209e141e72 Added Reference https://git.kernel.org/stable/c/2e67c2037382abb56497bb9d7b7e10be04eb5598 Added Reference https://git.kernel.org/stable/c/3fba965a9aac0fa3cbd8138436a37af9ab466d79 Added Reference https://git.kernel.org/stable/c/7404ce888a45eb7da0508b7cbbe6f2e95302eeb8 Added Reference https://git.kernel.org/stable/c/b6bfe44b6dbb14a31d86c475cdc9c7689534fb09 Added Reference https://git.kernel.org/stable/c/f36a305d30f557306d87c787ddffe094ac5dac89