CVE-2026-49412

High

Description

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.

SeverityHigh

CVSS7.8

Exploit probability—

Product

Freebsd

PublishedJun 27, 2026

First seenJun 27, 2026

Weakness typeCWE-416Use after free

How to fix

Vendor advisories

security.freebsd.org/advisories/FreeBSD-SA-26:29.ip6_multicast.asc

Affected products

Product	Affected versions	Fixed in
freebsd freebsd	14.3, 14.4, 15.0	—

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