CVE-2026-49419 — Jail reference count underflow

Description (CNA)

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.

Affected (CNA)

Vendor / product	Versions
FreeBSD / FreeBSD	affected 15.1-RELEASE before p1; affected 15.0-RELEASE before p11

CWE

CWE-911

References

https://security.freebsd.org/advisories/FreeBSD-SA-26:38.jail.asc

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.