FreeBSD: IPV6_MSFILTER UAF for Privilege Escalation
CVE-2026-49412 Published on June 27, 2026

Use-after-free bug in the IPV6_MSFILTER socket option handler
The kernel handler for IPV6_MSFILTER dropped a serializing lock in order to copy the source-filter list from userspace, then reacquired the lock. During this window another thread could free the multicast filter structure, leaving the handler with a stale pointer to freed memory. An unprivileged local user can exploit this use-after-free to escalate privileges.

Vendor Advisory NVD

Vulnerability Analysis

CVE-2026-49412 is exploitable with local system access, and requires small amount of user privileges. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to be very high.

Attack Vector:
LOCAL
Attack Complexity:
LOW
Privileges Required:
LOW
User Interaction:
NONE
Scope:
UNCHANGED
Confidentiality Impact:
HIGH
Integrity Impact:
HIGH
Availability Impact:
HIGH

Weakness Type

What is a Dangling pointer Vulnerability?

Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code.

CVE-2026-49412 has been classified to as a Dangling pointer vulnerability or weakness.


Products Associated with CVE-2026-49412

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Affected Versions

FreeBSD: