CVE-2026-49419

Panic or LPE via prison refcount underflow

Published Aug 19, 2026 · Updated Aug 20, 2026

Reference count underflow in FreeBSD before 15.0-RELEASE-p11 and 15.1-RELEASE-p1 allows local users to crash the host via failed jail descriptor lookups. In kern_jail_set() and kern_jail_get(), the JAIL_AT_DESC path drops the caller's current prison reference before jaildesc_find(); if lookup fails, the error path releases that same reference again, underflowing the prison refcount and leaving the prison structure eligible to be freed while still referenced. An unprivileged local user can reach the bug; on the jail host it generally causes an immediate panic, while a process already confined in a jail may be able to turn the stale prison reference into privilege escalation.

CVSS severity8.8
High
EPSS probability0.29%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Reference count underflow in FreeBSD before 15.0-RELEASE-p11 and 15.1-RELEASE-p1 allows local users to crash the host via failed jail descriptor lookups. In kern_jail_set() and kern_jail_get(), the JAIL_AT_DESC path drops the caller's current prison reference before jaildesc_find(); if lookup fails, the error path releases that same reference again, underflowing the prison refcount and leaving the prison structure eligible to be freed while still referenced. An unprivileged local user can reach the bug; on the jail host it generally causes an immediate panic, while a process already confined in a jail may be able to turn the stale prison reference into privilege escalation.

The record

CVE
CVE-2026-49419
Published
Aug 19, 2026
Updated
Aug 20, 2026
Vendor
The FreeBSD Project
Product
FreeBSD
Classifications
CWE-911, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 19, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 20, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=15.0-RELEASE <p11
  2. Affected versionversion=15.1-RELEASE <p1

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The FreeBSD Project · FreeBSDversion=15.0-RELEASE <p11; version=15.1-RELEASE <p1

Published CVSS scores

8.8GitHub Advisory DatabaseCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-911Improper Update of Reference Count
T1068Exploitation for Privilege Escalation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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