CVE-2025-40183: Linux kernel · bpf: Fix metadata_dst leak __bpf_redirect_neigh_v{4,6}
Source GCVE Database
Not known to be exploited · CVSS 7.5 High.
Data as of 26 Oct 2026, 17:16 UTC
- EPSS
- 0.6% chance of exploitation in 30 days – higher than 49% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 13 Nov 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
AI-suggested
Until an official fix is available, users should monitor kernel memory usage on affected systems and consider disabling or limiting the use of the BPF egress gateway feature with vxlan tunnels if feasible. Follow updates from the Linux kernel maintainers and Cilium project for patches addressing this issue.
Description
A vulnerability in the Linux kernel related to the bpf_redirect_neigh() helper caused a memory leak of metadata_dst objects in the kernel's kmalloc-256 slab. This issue affected the BPF egress gateway feature used by Cilium for Kubernetes pod traffic, where vxlan tunnels allocate metadata_dst objects that were not properly released. The leak occurs because bpf_redirect_neigh() sets a new destination entry without releasing the previous one, leading to increasing kernel memory usage over time.
References
- nvd.nist.gov/vuln/detail/CVE-2025-40183 (opens in a new tab)
- git.kernel.org/stable/c/057764172fcc6ee2ccb6c41351a55a9f054dc8fd (opens in a new tab)
- git.kernel.org/stable/c/23f3770e1a53e6c7a553135011f547209e141e72 (opens in a new tab)
- git.kernel.org/stable/c/2e67c2037382abb56497bb9d7b7e10be04eb5598 (opens in a new tab)
- git.kernel.org/stable/c/3fba965a9aac0fa3cbd8138436a37af9ab466d79 (opens in a new tab)
- git.kernel.org/stable/c/7404ce888a45eb7da0508b7cbbe6f2e95302eeb8 (opens in a new tab)
- git.kernel.org/stable/c/b6bfe44b6dbb14a31d86c475cdc9c7689534fb09 (opens in a new tab)
- git.kernel.org/stable/c/f36a305d30f557306d87c787ddffe094ac5dac89 (opens in a new tab)