CVE-2020-25584

Jail escape via mount lookup race

Published Apr 7, 2021 · Updated Aug 4, 2024

A jail-mount race in FreeBSD 11.4 through 13.0 allows local users with jail superuser privileges to read and write the host filesystem. The kernel resolves a parent-directory entry while a filesystem can be remounted over the jail root, letting the process cross the jail boundary. Exploitation requires superuser privileges inside a jail with the non-default allow.mount permission and grants full access to host files and directories.

CVSS severity7.5
High
EPSS probability0.18%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

A jail-mount race in FreeBSD 11.4 through 13.0 allows local users with jail superuser privileges to read and write the host filesystem. The kernel resolves a parent-directory entry while a filesystem can be remounted over the jail root, letting the process cross the jail boundary. Exploitation requires superuser privileges inside a jail with the non-default allow.mount permission and grants full access to host files and directories.

The record

CVE
CVE-2020-25584
Published
Apr 7, 2021
Updated
Aug 4, 2024
Vendor
The FreeBSD Project
Product
FreeBSD
Classifications
CWE-362, T1611
Attack vector
local
Privileges
admin

Timeline

How it unfolded

  1. Apr 7, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record 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=FreeBSD 12.2-RELEASE before p6, 11.4-RELEASE before p9

What conditions does exploitation require?

Attack vectorlocal
Required privilegesadmin

What is affected?

The FreeBSD Project · FreeBSDversion=FreeBSD 12.2-RELEASE before p6, 11.4-RELEASE before p9

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H
6.2NIST NVDAV:L/AC:H/Au:N/C:C/I:C/A:C

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-362Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
T1611Escape to Host

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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