CVE-2026-49412

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.

PUBLISHED Reserved 2026-05-29 | Published 2026-06-27 | Updated 2026-06-27 | Assigner freebsd

Problem types

CWE-416: Use After Free

Product status

Credits

Andrew Griffiths at Calif.io finder

Maik Münch finder

References

security.freebsd.org/...s/FreeBSD-SA-26:29.ip6_multicast.asc vendor-advisory

cve.org (CVE-2026-49412)

nvd.nist.gov (CVE-2026-49412)

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