Null Pointer Dereference Vulnerability in Linux Kernel's VXLAN Implementation
CVE-2025-39851

5.5MEDIUM

Key Information:

Vendor

Linux

Status
Vendor
CVE Published:
19 September 2025

What is CVE-2025-39851?

A vulnerability in the Linux kernel’s VXLAN implementation can lead to a null pointer dereference when handling FDB entries. In scenarios where learning is enabled, incoming packets that attempt to refresh FDB entries pointing to a nexthop group may not be properly dropped. This oversight occurs because the drop action is executed only after dereferencing a non-existent remote, which can result in a system crash. The issue has been fixed by ensuring packets are dropped at an earlier stage, thereby mitigating the risk of such dereferencing in future packet processing.

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Affected Version(s)

Linux 1274e1cc42264d4e629841e4f182795cb0becfd2 < 4ff4f3104da6507e0f118c63c4560dfdeb59dce3

Linux 1274e1cc42264d4e629841e4f182795cb0becfd2 < 0e8630f24c14d9c655d19eabe2e52a9e9f713307

Linux 1274e1cc42264d4e629841e4f182795cb0becfd2 < 6ead38147ebb813f08be6ea8ef547a0e4c09559a

References

CVSS V3.1

Score:
5.5
Severity:
MEDIUM
Confidentiality:
None
Integrity:
None
Availability:
None
Attack Vector:
Local
Attack Complexity:
Low
Privileges Required:
Low
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

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