CVE-2026-49419 Jail reference count underflow
An unprivileged local user can trigger a reference count underflow in FreeBSD jails, potentially leading to privilege escalation or system panic.
- 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-2026-49419?
CVE-2026-49419 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
When the JAIL_AT_DESC flag is specified, kern_jail_set() and kern_jail_get() released the reference to the caller's current prison before looking up the jail descriptor. If the descriptor lookup failed, error-handling paths released the same reference a second time.
An unprivileged local user can trigger a prison reference count underflow, which may cause the prison structure to be freed while still in use. When this is done on the jail host, the bug will generally result in an immediate panic. However, if the user is running in a jail, then it may be possible to exploit the bug to elevate privileges.
Weakness: CWE-911
Which versions are affected by CVE-2026-49419?
It affects 1 product.
Products include Freebsd Freebsd.
How do I fix CVE-2026-49419?
No fix has been published for CVE-2026-49419 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-2026-49419 being exploited?
There is no known exploitation of CVE-2026-49419 in the wild and no public exploit code.
Other vulnerabilities in Freebsd Freebsd
Sources
Also known as GHSA-w2h3-c2wj-whwm.