CVE-2025-21763 neighbour: use RCU protection in __neigh_notify()

What is CVE-2025-21763?

CVE-2025-21763 is a high-severity use after free vulnerability in Linux kernel, published on 27 Feb 2025. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

In the Linux kernel, the following vulnerability has been resolved:

neighbour: use RCU protection in __neigh_notify()

__neigh_notify() can be called without RTNL or RCU protection.

Use RCU protection to avoid potential UAF.

Weakness: CWE-416

Which versions are affected by CVE-2025-21763?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2025-21763?

Apply the vendor's patch.

Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.

Is CVE-2025-21763 being exploited?

There is no known exploitation of CVE-2025-21763 in the wild and no public exploit code.

Other vulnerabilities in Linux kernel

• CVE-2026-53266 Linux Kernel Out-of-Bounds Write Exploited High 8.8
• CVE-2013-6282 Linux Kernel Improper Input Validation Exploited High 8.8
• CVE-2022-0185 Linux Kernel Heap-Based Buffer Overflow Exploited High 8.4
• CVE-2013-2094 Linux Kernel Privilege Escalation Exploited High 8.4
• CVE-2026-53362 Linux Kernel Unspecified Exploited High 7.8

All Linux kernel vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as AZL-58911, AZL-58929, BELL-CVE-2025-21763, DEBIAN-CVE-2025-21763, GHSA-798h-hm78-q979, ROOT-OS-UBUNTU-2404-CVE-2025-21763 and 1 more.