CVE-2026-49412 Use-after-free bug in the IPV6_MSFILTER socket option handler
A use-after-free in the FreeBSD kernel's IPV6_MSFILTER handler allows local attackers to escalate privileges.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-49412?
CVE-2026-49412 is a high-severity use after free vulnerability in Freebsd Freebsd, published on 27 Jun 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official 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.
Weakness: CWE-416
Which versions are affected by CVE-2026-49412?
It affects 1 product.
Products include Freebsd Freebsd.
How do I fix CVE-2026-49412?
No fix has been published for CVE-2026-49412 yet. Limit exposure of the affected software until one is available.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-49412 being exploited?
There is no known exploitation of CVE-2026-49412 in the wild and no public exploit code.