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FreeBSDOperating system

CVE-2020-7454

CRITICAL · 9.8 CVSS v3.1 Published 2020-05-13
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges 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 12.1-STABLE before r360971, 12.1-RELEASE before p5, 11.4-STABLE before r360971, 11.4-BETA1 before p1 and 11.3-RELEASE before p9, libalias does not properly validate packet length resulting in modules causing an out of bounds read/write condition if no checking was built into the module.

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 buffer bounds validation vulnerability exists in FreeBSD's libalias module (used for NAT and connection tracking). The module fails to properly validate packet length fields, allowing out-of-bounds read/write operations when modules lack their own bounds checking. This memory corruption vulnerability can be triggered remotely via crafted network packets.

MitigationUpdate FreeBSD systems to version 12.1-STABLE r360971+, 12.1-RELEASE p5+, 11.4-STABLE r360971+, 11.4-BETA1 p1+, or 11.3-RELEASE p9+ to receive the patched libalias module.

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:= 11.3= 11.4= 12.1

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
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/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. Identify FreeBSD version
    Run 'uname -r' or 'freebsd-version -k' to obtain the installed FreeBSD version number
    Affected if The version begins with 11.3, 11.4, or 12.1 (without the required patch level)
  2. Check patch level on 12.1
    For 12.1 systems, run 'freebsd-version -u' and compare the build identifier against '12.1-RELEASE-p5' or later
    Affected if Running 12.1-RELEASE-p4 or earlier without the r360971 stable update
  3. Check patch level on 11.4
    For 11.4 systems, run 'freebsd-version -u' and compare the build identifier against '11.4-BETA1-p1' or later, or '11.4-STABLE' with r360971+
    Affected if Running 11.4-RELEASE or 11.4-BETA1 without the required patch level
  4. Check patch level on 11.3
    For 11.3 systems, run 'freebsd-version -u' and compare the build identifier against '11.3-RELEASE-p9' or later
    Affected if Running 11.3-RELEASE-p8 or earlier without the p9 or later patch
  5. Verify libalias module status
    Run 'kldstat | grep libalias' or check if NAT-related services (natd, ipfw nat, pf nat) are active, as the vulnerability only affects systems using the libalias functionality
    Affected if libalias module is loaded or NAT services are running on a vulnerable FreeBSD version

A system is affected if it runs FreeBSD 11.3, 11.4, or 12.1 without the respective patched version (11.3-RELEASE-p9+, 11.4-STABLE r360971+/11.4-BETA1-p1+, 12.1-STABLE r360971+/12.1-RELEASE-p5+) AND has the libalias module loaded or NAT functionality in use.

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.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Update FreeBSD systems to version 12.1-STABLE r360971+, 12.1-RELEASE p5+, 11.4-STABLE r360971+, 11.4-BETA1 p1+, or 11.3-RELEASE p9+ to receive the patched libalias module.

Recommended fix High confidence

FreeBSD 12.1-RELEASE p5+, FreeBSD 11.4-STABLE r360971+, FreeBSD 11.3-RELEASE p9+, or preferably FreeBSD 13-STABLE/14-CURRENT

  1. Identify current FreeBSD version using 'uname -r'
  2. For FreeBSD 11.3-RELEASE: Apply security patch p9 or later via freebsd-update or upgrade to 11.4/12.x/13.x
  3. For FreeBSD 11.4-STABLE or 11.4-BETA1: Update to stable branch after r360971 or upgrade to 12.x/13.x
  4. For FreeBSD 12.1-RELEASE: Apply security patch p5 or later via freebsd-update
  5. For FreeBSD 12.1-STABLE: Update to stable branch after r360971
  6. Alternatively, upgrade to FreeBSD 13-STABLE or later for long-term support
  7. After upgrade, verify libalias module loads correctly and test network address translation functionality
Caveat Major version upgrades (e.g., 11.x to 12.x or 13.x) may require testing of custom configurations and may introduce changes to system utilities, kernel modules, or defaults; review FreeBSD release notes before upgrading

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in FreeBSD Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing6.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,380
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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-2020-7454 in production — separate from our analysis above.

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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
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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  • No spam, self-promotion, credentials, or personal data