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OpensshApplication · OpenBSD

CVE-2003-0786

HIGH · 10.0 CVSS v2.0 Published 2003-11-17
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
The SSH1 PAM challenge response authentication in OpenSSH 3.7.1 and 3.7.1p1, when Privilege Separation is disabled, does not check the result of the authentication attempt, which can allow remote attackers to gain privileges.

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

In OpenSSH 3.7.1 and 3.7.1p1, the SSH1 PAM challenge-response authentication module fails to verify the authentication result when Privilege Separation is disabled. This allows any remote attacker to bypass authentication entirely and gain full user privileges on the system.

MitigationEnable Privilege Separation in sshd_config (set 'UsePrivilegeSeparation yes'), upgrade to a patched OpenSSH version, and disable the deprecated SSH1 protocol if not required.

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
OpensshApplication
Affected:= 3.7.1= 3.7.1p1

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
Authentication
None
Confidentiality
Complete
Integrity
Complete
Availability
Complete

AV:N/AC:L/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 installed OpenSSH version
    Run 'sshd -v' or 'sshd -V' to display the version, or check the package version via 'pkg_info -a | grep openssh'
    Affected if Version is 3.7.1 or 3.7.1p1 on OpenBSD
  2. Verify the operating system
    Run 'uname -a' to confirm the OS is OpenBSD
    Affected if Operating system is OpenBSD and OpenSSH version is 3.7.1 or 3.7.1p1
  3. Check Privilege Separation configuration
    Examine /etc/ssh/sshd_config for the 'UsePrivilegeSeparation' directive. Run 'grep -i UsePrivilegeSeparation /etc/ssh/sshd_config'
    Affected if UsePrivilegeSeparation is set to 'no' or 'disabled', or the directive is absent (defaults to no in vulnerable versions)
  4. Confirm SSH1 protocol is enabled
    Examine /etc/ssh/sshd_config for 'Protocol 1' or check if the SSH1 implementation is active. Run 'grep -i Protocol /etc/ssh/sshd_config'
    Affected if Protocol is set to 1, or the default setting allows SSH1 connections

User is affected if running OpenSSH 3.7.1 or 3.7.1p1 on OpenBSD with Privilege Separation disabled, and SSH1 protocol connections are permitted.

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

Enable Privilege Separation in sshd_config (set 'UsePrivilegeSeparation yes'), upgrade to a patched OpenSSH version, and disable the deprecated SSH1 protocol if not required.

Recommended fix High confidence

OpenSSH 3.7.2 or later stable release

  1. 1. Identify current OpenSSH version by running: sshd -v or rpm -q openssh (or dpkg -l openssh-server for Debian/Ubuntu)
  2. 2. Verify the installed version is 3.7.1 or 3.7.1p1: openssh-server -v 2>&1 | grep -i openssh
  3. 3. Update your system's package repository metadata: yum clean all (RHEL/CentOS) or apt-get update (Debian/Ubuntu)
  4. 4. Upgrade OpenSSH to version 3.7.2 or later: yum update openssh (RHEL/CentOS) or apt-get install openssh-server (Debian/Ubuntu)
  5. 5. Verify the new version is installed: rpm -q openssh-server or dpkg -l openssh-server
  6. 6. Ensure Privilege Separation is enabled in /etc/ssh/sshd_config (the default since OpenSSH 3.2.2+), verify the line 'UsePrivilegeSeparation yes' exists and is not set to 'no'
  7. 7. Restart the SSH daemon to apply changes: service sshd restart or systemctl restart sshd
Caveat Minimal risk; ensure SSH key-based authentication is working before restarting the SSH daemon to avoid lockout

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

Fix this in Openssh Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
7.0 hours of engineering $1,240
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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-2003-0786 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