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FreesshdApplication

CVE-2012-6066

HIGH · 9.3 CVSS v2.0 Published 2012-12-04
Fix available
A fix is available. Upgrade to after 1.2.6 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
freeSSHd.exe in freeSSHd through 1.2.6 allows remote attackers to bypass authentication via a crafted session, as demonstrated by an OpenSSH client with modified versions of ssh.c and sshconnect2.c.

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 · moderate confidence

freeSSHd through version 1.2.6 contains an authentication bypass vulnerability that allows remote attackers to gain unauthorized access via a crafted SSH session. The attack involves modifying the OpenSSH client source files (ssh.c and sshconnect2.c) to send specially crafted packets that circumvent the authentication mechanism.

MitigationUpgrade freeSSHd to a patched version if available, or migrate to a maintained SSH server implementation (such as Bitvise WinSSHD, OpenSSH for Windows, or native Windows OpenSSH). If upgrade is not possible, restrict network access to the SSH service using firewall rules or VPN access controls.

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
FreesshdApplication
Affected:<= 1.2.6= 1.2.1= 1.2.2

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
M
Authentication
None
Confidentiality
Complete
Integrity
Complete
Availability
Complete

AV:N/AC:M/Au:N/C:C/I:C/A:C

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 if freeSSHd is installed
    Check for freeSSHd service or executable on the system. Look for the service named 'freeSSHd' in Windows Services, or check for installation directory (typically C:\Program Files\freeSSHd or C:\freeSSHd) and the freesshd.exe executable.
    Affected if freeSSHd executable or service is found on the system
  2. Determine freeSSHd version
    Right-click on freesshd.exe, select Properties, then go to the Details tab to view the File Version. Alternatively, run 'freesshd.exe -v' from command line if supported, or check the version in the Windows Services properties.
    Affected if The installed version is 1.2.6 or lower, or specifically versions 1.2.1, 1.2.2, or any version up to 1.2.6
  3. Verify SSH service is running and listening
    Check if the freeSSHd service is running (in Windows Services or via 'sc query freeSSHd' command). Use 'netstat -an | findstr :22' to verify port 22 (or configured SSH port) is listening.
    Affected if The freeSSHd service is running and listening on a network port, making it accessible to remote attackers
  4. Check network exposure
    Review firewall rules and network configuration to determine if the SSH port is exposed to untrusted networks. Use 'netsh advfirewall firewall show rule name=all' or check Windows Firewall inbound rules for freeSSHd.
    Affected if The SSH service is accessible from untrusted or external networks (not limited to localhost or VPN-only access)
  5. Confirm authentication configuration
    Open freeSSHd GUI or check its configuration file (usually freeSSHd.xml in the installation directory or user profile) to verify that password or public key authentication is enabled.
    Affected if Authentication methods other than 'None' or disabled are configured, as the bypass targets the authentication mechanism

The environment is affected if freeSSHd version 1.2.6 or lower is installed, the service is running and network-accessible, and the SSH authentication mechanism is enabled.

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 a release after 1.2.6
Interim mitigation

Upgrade freeSSHd to a patched version if available, or migrate to a maintained SSH server implementation (such as Bitvise WinSSHD, OpenSSH for Windows, or native Windows OpenSSH). If upgrade is not possible, restrict network access to the SSH service using firewall rules or VPN access controls.

Recommended fix High confidence
  1. 1. If freeSSHd is not critical to operations, uninstall or disable the service immediately.
  2. 2. If freeSSHd must remain in use, restrict network access to the SSH service (port 22) using firewall rules to allow only trusted source IP addresses.
  3. 3. Implement additional network segmentation to isolate the freeSSHd server from sensitive systems.
  4. 4. Monitor authentication logs for unusual login patterns or failed authentication attempts.
  5. 5. Consider migrating to an actively maintained SSH server solution such as OpenSSH for Windows or Bitvise SSH Server if authentication security is critical.
Caveat freeSSHd appears to be abandoned with no patched version available; no upgrade path exists

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

Fix this in Freesshd Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing2.0 h
  • Review / QA1.0 h
9.0 hours of engineering $1,600
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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-2012-6066 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