CVE-2026-49412

Use-after-free bug in the IPV6_MSFILTER socket option handler

State: Published
Severity: 7.8 High
Published: Jun 27, 2026
Updated: Jun 30, 2026
Reserved: May 29, 2026

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.

Scores

CVSS	Score	Vector	Source
3.1	7.8 High	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H	CISA-ADP

Weaknesses

CWE-416 Use After Free

Affected Products

Product	Versions
FreeBSDFreeBSD	15.0-RELEASE to before p10Affected 14.4-RELEASE to before p6Affected 14.3-RELEASE to before p15Affected

References

https://security.freebsd.org/advisories/FreeBSD-SA-26:29.ip6_multicast.ascvendor-advisory

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