ndisc: use RCU protection in ndisc_alloc_skb()
CVE: CVE-2025-21764
Component: kernel
CWE: CWE-416
Severity: Moderate
CVSS v3: 7.0/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Release date: 2025-02-27T00:00:00+00:00

A vulnerability was found in the Linux kernel's IPv6 Neighbor Discovery (NDISC) subsystem, which manages network neighbor information. The issue arises from improper synchronization mechanisms when allocating socket buffers (sk_buff) in the ndisc_alloc_skb() function. Specifically, the function can be called without holding the necessary Read-Copy-Update (RCU) or Routing Netlink (RTNL) locks, leading to a potential use-after-free (UAF) condition. This flaw allows an attacker with local access and low privileges to exploit the race condition, potentially causing system instability or crashes.

Statement: Red Hat Product Security has rated this bug as Moderate due to the following:

Difficult to exploit reliably:
* Requires winning a race condition in the kernel.
* No known public PoC or exploitation.
* Might be nondeterministic and hard to control memory reuse.

May not lead to code execution:
* Use After Free doesn’t automatically mean control.
* Many kernel UAFs cause crashes but not privilege escalation or info leaks unless paired with other bugs.

Limited exposure:
* Requires IPv6 to be enabled.
* Possibly depends on attacker having raw socket access or other local privileges.
* Mitigations Like KASLR, SLAB hardening, and SELinux may further reduce practical risk.

Remediation:
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.