CVE-2025-39850

Kernel crash via VXLAN null pointer dereference

Published Sep 19, 2025 · Updated Sep 19, 2025

NULL pointer dereference in Linux kernel VXLAN 5.8 and later affected releases allows local users to crash the kernel. The arp_reduce and neigh_reduce paths assume an FDB entry has a remote destination and dereference a null pointer when that entry instead uses a nexthop group. Reachability requires local access and a proxy-enabled VXLAN device with matching neighbor and FDB nexthop-group entries; the observed consequence is a kernel crash.

CVSS severity5.5
Medium
EPSS probability0.14%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

NULL pointer dereference in Linux kernel VXLAN 5.8 and later affected releases allows local users to crash the kernel. The arp_reduce and neigh_reduce paths assume an FDB entry has a remote destination and dereference a null pointer when that entry instead uses a nexthop group. Reachability requires local access and a proxy-enabled VXLAN device with matching neighbor and FDB nexthop-group entries; the observed consequence is a kernel crash.

The record

CVE
CVE-2025-39850
Published
Sep 19, 2025
Updated
Sep 19, 2025
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-476, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 19, 2025CVE publishedPublication date reported by the CVE source.
  2. Sep 19, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=1274e1cc42264d4e629841e4f182795cb0becfd2 <1f5d2fd1ca04a23c18b1bde9a43ce2fa2ffa1bce
  2. Affected versionversion=1274e1cc42264d4e629841e4f182795cb0becfd2 <8cfa0f076842f9b3b4eb52ae0e41d16e25cbf8fa
  3. Affected versionversion=1274e1cc42264d4e629841e4f182795cb0becfd2 <e211e3f4199ac829bd493632efcd131d337cba9d
  4. Affected versionversion=5.8

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=1274e1cc42264d4e629841e4f182795cb0becfd2 <1f5d2fd1ca04a23c18b1bde9a43ce2fa2ffa1bce; version=1274e1cc42264d4e629841e4f182795cb0becfd2 <8cfa0f076842f9b3b4eb52ae0e41d16e25cbf8fa; version=1274e1cc42264d4e629841e4f182795cb0becfd2 <e211e3f4199ac829bd493632efcd131d337cba9d; version=5.8

Published CVSS scores

5.5CISA ADP VulnrichmentCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-476NULL Pointer Dereference
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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