dbcve.org
FreeBSDOperating system

CVE-2016-1888

HIGH · 7.5 CVSS v3.0 Published 2017-02-15
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
84/100
Remediation priority · High
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
The telnetd service in FreeBSD 9.3, 10.1, 10.2, 10.3, and 11.0 allows remote attackers to inject arguments to login and bypass authentication via vectors involving a "sequence of memory allocation failures."

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 telnetd daemon in multiple FreeBSD versions (9.3, 10.1-10.3, 11.0) contains a vulnerability where a sequence of memory allocation failures allows remote attackers to inject arguments to the login program and bypass authentication mechanisms.

MitigationDisable the telnetd service immediately and restrict telnet access at the network perimeter. Migrate to SSH for remote administrative access. If telnet is business-critical, apply vendor patches and limit network exposure.

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:= 9.3= 10.1= 10.2= 10.3= 11.0

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
None
Integrity
High
Availability
None

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

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 -a` or `freebsd-version -u` to determine the installed FreeBSD version
    Affected if The version matches 9.3, 10.1, 10.2, 10.3, or 11.0
  2. Check if telnetd is enabled in system configuration
    Inspect /etc/rc.conf for the line `telnetd_enable="YES"`
    Affected if telnetd_enable is set to YES
  3. Check if telnetd process is running
    Run `ps aux | grep telnetd` to see if the telnetd daemon is actively running
    Affected if A telnetd process is running and visible in the process list
  4. Verify telnet service is listening on the network
    Run `sockstat -4 | grep :23` or `netstat -an | grep LISTEN | grep :23` to check if port 23 is open and listening
    Affected if Port 23 is in LISTEN state and accepting connections

A user is affected if their FreeBSD version is 9.3, 10.1, 10.2, 10.3, or 11.0 AND telnetd is enabled or running on the system

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

Disable the telnetd service immediately and restrict telnet access at the network perimeter. Migrate to SSH for remote administrative access. If telnet is business-critical, apply vendor patches and limit network exposure.

Fix this in FreeBSD Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing1.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,090
Get help mitigating

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,744.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

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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-2016-1888 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
  • 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