CVE-2026-49428 posixshm: system calls can incorrectly free memory of largepage objects

High 8.4 Published 19 Aug 2026 Updated 20 Aug 2026

An unprivileged local user can exploit a use-after-free bug in FreeBSD kernel system calls to access freed memory and escalate privileges.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Local or same network only
Victim action needed: Not needed
Fix: None listed

What is CVE-2026-49428?

CVE-2026-49428 is a high-severity use after free vulnerability in Freebsd Freebsd, published on 19 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

Certain system calls, such open(2) with the O_TRUNC flag set, and fspacectl(2), could incorrectly free memory in largepage objects. These operations are not permitted on largepage objects, but the implementation did not verify this.

An unprivileged local user can abuse the bug to access freed kernel memory. This can be exploited to escalate privileges.

Weakness: CWE-915

Which versions are affected by CVE-2026-49428?

It affects 1 product.

Products include Freebsd Freebsd.

How do I fix CVE-2026-49428?

No fix has been published for CVE-2026-49428 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-2026-49428 being exploited?

There is no known exploitation of CVE-2026-49428 in the wild and no public exploit code.

All Freebsd Freebsd vulnerabilities

Sources

Also known as GHSA-7m85-fgv2-gv39.