Jail reference count underflow
Summary
| CVE | CVE-2026-49419 |
|---|---|
| State | PUBLISHED |
| Assigner | freebsd |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-08-19 05:17:04 UTC |
| Updated | 2026-08-19 05:17:04 UTC |
| 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. |
Risk And Classification
Problem Types: CWE-911 | CWE-911 CWE-911: Improper Update of Reference Count
Vendor Declared Affected Products
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| security.freebsd.org/advisories/FreeBSD-SA-26:38.jail.asc | [email protected] | security.freebsd.org | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: Yuxiang Yang, Yizhou Zhao, Ao Wang, Xuewei Feng, Qi Li, and Ke Xu from Tsinghua University using GLM-5.1 from Z.ai (en)
There are currently no legacy QID mappings associated with this CVE.