Debian LinuxOperating system · Debian
CVE-2016-6318
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 · uneditedStack-based buffer overflow in the FascistGecosUser function in lib/fascist.c in cracklib allows local users to cause a denial of service (application crash) or gain privileges via a long GECOS field, involving longbuffer.
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 confidenceA stack-based buffer overflow exists in the FascistGecosUser function in lib/fascist.c of the cracklib library. The function fails to properly bounds-check the GECOS field (user information field in /etc/passwd), allowing a local user with the ability to modify their GECOS field to overflow a stack buffer, potentially causing a denial of service via crash or achieving privilege escalation.
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
= 8.0>= 2.9.0, < 2.9.6= 42.1CVSS 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
- Low
- Privileges
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:L/AC:L/PR:L/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 checksWork through these to decide whether this CVE applies to you.
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Identify if cracklib is installedRun 'dpkg -l | grep cracklib' (Debian) or 'rpm -qa | grep cracklib' (RPM-based) to list installed cracklib packagesAffected if No cracklib packages are found, meaning the library is not present and the vulnerability does not apply
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Determine cracklib versionRun 'dpkg -l libcrack2' or 'rpm -q libcrack2' to get the installed version numberAffected if The installed version is >= 2.9.0 and < 2.9.6, or matches Debian 8.0 or Opensuse Leap 42.1 which are in the affected range
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Verify if programs use FascistGecosUserCheck for binaries that link against cracklib and perform password checking, such as 'passwd', 'chpasswd', or custom applications. Use 'ldd /usr/bin/passwd' or search for binaries calling cracklib functionsAffected if The FascistGecosUser function is actively used by password-related programs on the system
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Check if users can modify their GECOS fieldExamine /etc/passwd permissions (ls -l /etc/passwd) and verify if standard users can run 'chfn' to modify their GECOS field. Also check PAM configuration for cracklib usage in password policiesAffected if Standard users have the ability to modify their GECOS field, allowing them to trigger the overflow
A system is affected if cracklib version 2.9.0 through 2.9.6 (or the specific distro versions) is installed and programs using FascistGecosUser are active, combined with users having the ability to modify their GECOS field in /etc/passwd.
Generated from the published advisory. Verify against your own configuration.
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 data2.9.6
Apply the upstream patch for CVE-2016-6318 to cracklib which adds proper length validation when processing the GECOS field. Additionally, restrict/modify who can modify GECOS fields in /etc/passwd as a compensating control until the library is patched.
Fix this in Debian Linux
Scoped from the published advisory
- Consultation3.0 h
- Implementation4.0 h
- Testing4.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,648.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2016-6318 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2016-6318 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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