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Debian LinuxOperating system · Debian

CVE-2018-16947

CRITICAL · 9.8 CVSS v3.0 Published 2018-09-12
Fix available
A fix is available. Upgrade to 1.6.23 / 1.8.2 or later.
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
An issue was discovered in OpenAFS before 1.6.23 and 1.8.x before 1.8.2. The backup tape controller (butc) process accepts incoming RPCs but does not require (or allow for) authentication of those RPCs. Handling those RPCs results in operations being performed with administrator credentials, including dumping/restoring volume contents and manipulating the backup database. For example, an unauthenticated attacker can replace any volume's content with arbitrary data.

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

The backup tape controller (butc) in OpenAFS versions before 1.6.23 and 1.8.2 accepts unauthenticated RPCs and executes them with administrator privileges, allowing remote unauthenticated attackers to dump/restore volumes and replace any volume's content with arbitrary data.

MitigationUpgrade OpenAFS to version 1.6.23 or 1.8.2 or later to patch the authentication bypass, and restrict network access to the butc service to prevent external exploitation.

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
Debian LinuxOperating system
Affected:= 8.0= 9.0
OpenafsApplication
Affected:< 1.6.23>= 1.8.0, < 1.8.2

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

CVSS:3.0/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. Verify OpenAFS installation
    Check if OpenAFS client/server is installed by looking for the 'vos' command (vos --version) or checking for presence of /usr/vice/etc/afsd or /usr/afs directories. On Debian, also check dpkg -l | grep openafs.
    Affected if OpenAFS is not installed or no version can be determined - not vulnerable to this specific CVE.
  2. Determine installed OpenAFS version
    Run 'vos --version' or check the package version: dpkg -l openafs-client (Debian) or rpm -q openafs (RHEL). Compare against the affected ranges: < 1.6.23 OR >= 1.8.0 but < 1.8.2.
    Affected if Installed version falls within < 1.6.23 OR >= 1.8.0, < 1.8.2 - the version is vulnerable.
  3. Check if butc daemon is running
    Run 'ps aux | grep butc' or check process status. Also verify the butc port (default 7007) is listening: 'netstat -anp | grep 7007' or 'ss -tlnp | grep 7007'.
    Affected if butc daemon is actively running and listening on a network port - the vulnerability is exploitable.
  4. Verify butc RPC service exposure
    Confirm that the butc port (TCP/7007) is bound to a network interface accessible from outside localhost. Check /etc/openafs/butc.conf or /etc/afs/butc.conf for configuration, and review firewall rules or iptables for port 7007 accessibility.
    Affected if butc port 7007 is accessible from network hosts beyond localhost - remote exploitation is possible.

A system is affected if it runs OpenAFS version < 1.6.23 or >= 1.8.0 but < 1.8.2, has the butc daemon running, and exposes the butc RPC service (port 7007) to network-accessible interfaces.

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
Upgrade available Upgrade to 1.6.23 / 1.8.2 or later
Fixed in 1.6.231.8.2
Interim mitigation

Upgrade OpenAFS to version 1.6.23 or 1.8.2 or later to patch the authentication bypass, and restrict network access to the butc service to prevent external exploitation.

Recommended fix High confidence

OpenAFS 1.6.23 or 1.8.2 (or later stable release)

  1. 1. Identify the current OpenAFS version by running 'rxstat -version' or checking the package version with 'dpkg -l | grep openafs' or 'rpm -qa | grep openafs'
  2. 2. For Debian 8 (Jessie) and Debian 9 (Stretch): Run 'apt-get update' followed by 'apt-get upgrade openafs' or 'apt-get install openafs-client openafs-krb5 openafs-modules-dkms' to install the updated package
  3. 3. For OpenAFS from source: Download OpenAFS 1.6.23 or 1.8.2 (or later) from the official OpenAFS distribution site (download.openafs.org)
  4. 4. Stop all OpenAFS services: '/etc/init.d/openafs-client stop' and '/etc/init.d/openafs-server stop'
  5. 5. Install the new version following standard OpenAFS build procedures (./configure, make, make install)
  6. 6. Restart OpenAFS services: '/etc/init.d/openafs-server start' then '/etc/init.d/openafs-client start'
  7. 7. Verify the fix by checking the version: 'rxstat -version' should show 1.6.23, 1.8.2, or higher
Caveat Review OpenAFS release notes for any configuration or feature changes between your current version and the target fixed version; test in a non-production environment first

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

Fix this in Debian Linux Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing4.0 h
  • Review / QA2.0 h
12.0 hours of engineering $2,080
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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-2018-16947 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
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data