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Libpam ModulesPlugin / extension · Canonical

CVE-2011-3628

MEDIUM · 6.9 CVSS v2.0 Published 2014-04-15
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
74/100
Remediation priority · Elevated
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
Untrusted search path vulnerability in pam_motd (aka the MOTD module) in libpam-modules before 1.1.3-2ubuntu2.1 on Ubuntu 11.10, before 1.1.2-2ubuntu8.4 on Ubuntu 11.04, before 1.1.1-4ubuntu2.4 on Ubuntu 10.10, before 1.1.1-2ubuntu5.4 on Ubuntu 10.04 LTS, and before 0.99.7.1-5ubuntu6.5 on Ubuntu 8.04 LTS, when using certain configurations such as "session optional pam_motd.so", allows local users to gain privileges by modifying the PATH environment variable to reference a malicious command, as demonstrated via uname.

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

pam_motd executes external commands (like uname) without using absolute paths, allowing local users to manipulate the PATH environment variable to point to malicious executables. When a user logs in and pam_motd runs, it executes the PATH-modified command with elevated privileges, achieving local privilege escalation.

MitigationUpdate libpam-modules to the patched versions for affected Ubuntu releases, or remove pam_motd from PAM configuration if not needed. Ensure all executed commands in PAM configurations use absolute paths.

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
Libpam ModulesPlugin / extension
Affected:= 0.9.7= 1.1.1= 1.1.2= 1.1.3
Ubuntu LinuxOperating system
Affected:= 8.04= 10.04= 10.10= 11.04= 11.10

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
Local
Complexity
M
Authentication
None
Confidentiality
Complete
Integrity
Complete
Availability
Complete

AV:L/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. Verify if pam_motd is enabled in PAM configuration
    Search for pam_motd in PAM configuration files: grep -r "pam_motd" /etc/pam.d/ or check /etc/pam.d/login, /etc/pam.d/sshd, and /etc/pam.d/common-session files
    Affected if pam_motd is present and enabled in any PAM configuration file
  2. Check installed version of libpam-modules
    Run dpkg -l libpam-modules or apt-cache policy libpam-modules to retrieve the installed version number
    Affected if Installed version matches 0.9.7, 1.1.1, 1.1.2, or 1.1.3 exactly, or falls within the affected Ubuntu releases (8.04, 10.04, 10.10, 11.04, 11.10)
  3. Inspect motd scripts for non-absolute command paths
    Examine scripts in /etc/update-motd.d/ and /etc/motd for commands (like uname, hostname, etc.) invoked without full path prefixes (e.g., just "uname" instead of "/bin/uname")
    Affected if Any script executed by pam_motd contains commands without absolute paths (no leading /)
  4. Check PAM session configuration for pam_motd invocation
    Review /etc/pam.d/common-session and session-specific PAM config files for lines containing pam_motd.so to confirm it loads at login
    Affected if pam_motd.so module is loaded in a PAM session stack that runs during user authentication or session establishment

The system is affected if pam_motd is enabled in PAM configuration AND the installed libpam-modules version matches the vulnerable versions, particularly if motd scripts execute commands without absolute paths.

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

Update libpam-modules to the patched versions for affected Ubuntu releases, or remove pam_motd from PAM configuration if not needed. Ensure all executed commands in PAM configurations use absolute paths.

Fix this in Libpam Modules 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
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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-2011-3628 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
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  • Version or environment caveats, and links to real fixes
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