CVE-2026-49419: When the JAIL_AT_DESC flag is specified, kern_jail_set() and kern_jail_get() released the reference to the cal

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HIGH 8.8MITIGATE

CVE-2026-49419 is a high-severity flaw (CVSS 8.8) affecting freebsd. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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,

Why this priority

High severity

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	8.8 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.5% (top 60%)
CISA exploited list	No
Weakness	CWE-911
Published	2026-08-19
Last modified	2026-09-01

Publisher (CNA): FreeBSD · Vendor: freebsd

Last updated 2026-09-01 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-08-19 05:17 UTCPublished CVE record published
2026-09-01 20:20 UTCUpdated Record last modified

freebsd freebsd MITIGATE

Affected: 15.0 · 15.0 p1 · 15.0 p10 · 15.0 p2 · 15.0 p3 · 15.0 p4 · 15.0 p5 · 15.0 p6

Fixed in: no fixed release known

Safe to downgrade to: a release before 15.0

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-49419?

freebsd: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2026-49419 being exploited?

CVE-2026-49419 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-49419 affect?

CVE-2026-49419 affects freebsd. Severity is high (CVSS 8.8). 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 sa

How urgent is CVE-2026-49419?

Priority 41/100. High severity

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References

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