CVE-2026-49427 posixshm: largepage shared memory objects not explicitly wired
An unprivileged local user can exploit a use-after-free in FreeBSD's posixshm to access freed kernel memory and escalate privileges.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-49427?
CVE-2026-49427 is a high-severity use after free vulnerability in Freebsd Freebsd, published on 19 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
Pages belonging to largepage shared memory objects were not explicitly wired. When sendfile(2) transmitted such an object with the SF_NOCACHE flag, it freed the underlying pages after transmission even though existing mappings still referred to them.
An unprivileged local user can abuse the bug to access freed kernel memory. This can be exploited to escalate privileges.
Weakness: CWE-826
Which versions are affected by CVE-2026-49427?
It affects 1 product.
Products include Freebsd Freebsd.
How do I fix CVE-2026-49427?
No fix has been published for CVE-2026-49427 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-2026-49427 being exploited?
There is no known exploitation of CVE-2026-49427 in the wild and no public exploit code.