CVE-2026-49412

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

Published Jun 27, 2026 CVSS 3.1 · 7.8 High EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
Metrics cvssV3_1

{'score': 7.8, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'}

ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Freebsd
Freebsd freebsd
Vendors & Products Freebsd
Freebsd freebsd
Type Values Removed Values Added
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.
Title Use-after-free bug in the IPV6_MSFILTER socket option handler
Weaknesses CWE-416
References
Weaknesses

Sources

Status
PUBLISHED
Assigner
freebsd
Published
Updated
Jun 30, 2026, 3:55 AM
Reserved
May 29, 2026, 8:24 PM
Status
Analyzed
Published
Jun 27, 2026, 9:16 AM
Modified
Jul 1, 2026, 2:04 PM