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FreeBSDOperating system

CVE-2020-25581

HIGH · 7.5 CVSS v3.1 Published 2021-03-26
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
81/100
Remediation priority · High
Remotely reachable Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
In FreeBSD 12.2-STABLE before r369312, 11.4-STABLE before r369313, 12.2-RELEASE before p4 and 11.4-RELEASE before p8 due to a race condition in the jail_remove(2) implementation, it may fail to kill some of the processes.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A race condition in the jail_remove(2) system call implementation in FreeBSD 12.2 and 11.4 releases allows processes within a jail to potentially survive after the jail is removed. This occurs when the jail removal fails to properly terminate all associated processes due to timing issues in the kernel code.

MitigationUpgrade FreeBSD systems to 12.2-STABLE after r369312, 11.4-STABLE after r369313, 12.2-RELEASE p4 or later, or 11.4-RELEASE p8 or later to incorporate the race condition fix.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
FreeBSDOperating system
Affected:= 11.4= 12.2

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
High
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check FreeBSD release version
    Run 'uname -r' or 'freebsd-version -k' to obtain the installed FreeBSD version
    Affected if Version is 11.4 or 12.2 (exact releases, not -STABLE branches)
  2. Verify jail functionality is in use
    Run 'jls' to list active jails or check /etc/jail.conf for jail configurations
    Affected if Any jails are configured or running on the system
  3. Check for orphaned prison processes
    Run 'ps -ax | grep -E "^.*:.*jail.*"' to inspect processes with jail markings, then compare against active jail list from 'jls'
    Affected if Processes exist with jail affiliation but no corresponding jail ID in 'jls' output
  4. Review system logs for jail removal failures
    Examine /var/log/messages or use 'dmesg' for any messages containing 'jail_remove' or 'jail' during removal operations
    Affected if Jail removal operations logged failures or timing-related errors

System is affected if running FreeBSD 11.4 or 12.2 exact releases AND using jail functionality, where orphaned processes may persist after jail removal without explicit detection.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade FreeBSD systems to 12.2-STABLE after r369312, 11.4-STABLE after r369313, 12.2-RELEASE p4 or later, or 11.4-RELEASE p8 or later to incorporate the race condition fix.

Fix this in FreeBSD Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA1.0 h
10.0 hours of engineering $1,750
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Scan for this in your stack

Free · runs locally
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2020-25581 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
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  • Version or environment caveats, and links to real fixes
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