CVE-2026-49419
Jail reference count underflow
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.
INFO
Published Date :
Aug. 19, 2026, 5:17 a.m.
Last Modified :
Sept. 1, 2026, 8:20 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | HIGH | 134c704f-9b21-4f2e-91b3-4a467353bcc0 |
Solution
- Apply kernel patches for jail reference handling.
- Ensure jail descriptor lookups are safe.
- Test for privilege escalation vulnerabilities.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-49419.
| URL | Resource |
|---|---|
| https://security.freebsd.org/advisories/FreeBSD-SA-26:38.jail.asc | Vendor Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-49419 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-49419
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-49419 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-49419 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
Sep. 01, 2026
Action Type Old Value New Value Added CPE Configuration OR *cpe:2.3:o:freebsd:freebsd:15.0:p1:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:15.0:p2:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:15.0:-:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:15.0:p3:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:15.0:p4:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:15.0:p5:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:15.0:p6:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:15.0:p7:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:15.0:p8:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:15.0:p9:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:15.1:rc2:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:15.0:p10:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:15.1:-:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:15.1:rc3-p1:*:*:*:*:*:* Added Reference Type FreeBSD: https://security.freebsd.org/advisories/FreeBSD-SA-26:38.jail.asc Types: Vendor Advisory -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Aug. 20, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H Changed SSVC {'id': 'CVE-2026-49419', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'total'}], 'version': '2.0.3', 'timestamp': '2026-08-19T00:00:00+00:00'} {'id': 'CVE-2026-49419', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'total'}], 'version': '2.0.3', 'timestamp': '2026-08-20T03:56:04.011376Z'} -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Aug. 20, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-49419', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'total'}], 'version': '2.0.3', 'timestamp': '2026-08-19T00:00:00+00:00'} -
New CVE Received by [email protected]
Aug. 19, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'FreeBSD', 'modules': ['jail'], 'product': 'FreeBSD', 'versions': [{'status': 'affected', 'version': '15.1-RELEASE', 'lessThan': 'p1', 'versionType': 'release'}, {'status': 'affected', 'version': '15.0-RELEASE', 'lessThan': 'p11', 'versionType': 'release'}], 'defaultStatus': 'unknown'}] Added 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. Added CWE CWE-911 Added Reference https://security.freebsd.org/advisories/FreeBSD-SA-26:38.jail.asc