CVE-2026-49412: Use-after-free bug in the IPV6_MSFILTER socket option handler

Published Jun 27, 2026
·
Updated

The kernel handler for IPV6MSFILTER 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.

Affected Software

32 affected components
IPV6_MSFILTER
FreeBSD FreeBSD=14.3
FreeBSD FreeBSD=14.3-p1
FreeBSD FreeBSD=14.3-p10
FreeBSD FreeBSD=14.3-p11
FreeBSD FreeBSD=14.3-p12
FreeBSD FreeBSD=14.3-p13
FreeBSD FreeBSD=14.3-p14
FreeBSD FreeBSD=14.3-p2
FreeBSD FreeBSD=14.3-p3
FreeBSD FreeBSD=14.3-p4
FreeBSD FreeBSD=14.3-p5
FreeBSD FreeBSD=14.3-p6
FreeBSD FreeBSD=14.3-p7
FreeBSD FreeBSD=14.3-p8
FreeBSD FreeBSD=14.3-p9
FreeBSD FreeBSD=14.4
FreeBSD FreeBSD=14.4-p1
FreeBSD FreeBSD=14.4-p2
FreeBSD FreeBSD=14.4-p3
FreeBSD FreeBSD=14.4-p4
FreeBSD FreeBSD=14.4-p5
FreeBSD FreeBSD=15.0
FreeBSD FreeBSD=15.0-p1
FreeBSD FreeBSD=15.0-p2
FreeBSD FreeBSD=15.0-p3
FreeBSD FreeBSD=15.0-p4
FreeBSD FreeBSD=15.0-p5
FreeBSD FreeBSD=15.0-p6
FreeBSD FreeBSD=15.0-p7
FreeBSD FreeBSD=15.0-p8
FreeBSD FreeBSD=15.0-p9

Event History

Jun 27, 2026
CVE Published
via MITRE·09:02 AM
Data Sourced
via MITRE·09:02 AM
DescriptionWeakness
Data Sourced
via NVD·09:16 AM
DescriptionSeverityWeaknessAffected Software
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Frequently Asked Questions

1

What is the severity of CVE-2026-49412?

The severity of CVE-2026-49412 is rated at 72.

2

How do I fix CVE-2026-49412?

To fix CVE-2026-49412, update your system to the latest version of the software that addresses this vulnerability.

3

What systems are affected by CVE-2026-49412?

CVE-2026-49412 affects systems that utilize the IPV6_MSFILTER socket option.

4

What type of vulnerability is CVE-2026-49412?

CVE-2026-49412 is classified as a use-after-free vulnerability.

5

What could happen if CVE-2026-49412 is exploited?

Exploitation of CVE-2026-49412 could allow an unprivileged local attacker to execute arbitrary code or cause a denial of service.

Contact

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