Debian LinuxOperating system · Debian
CVE-2016-3992
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 · uneditedcronic before 3 allows local users to write to arbitrary files via a symlink attack on a (1) cronic.out.$$, (2) cronic.err.$$, or (3) cronic.trace.$$ file in /tmp.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · moderate confidenceCronic before version 3 creates temporary output files (cronic.out.$$, cronic.err.$$, cronic.trace.$$) in /tmp using predictable process ID ($$) filenames without proper symlink checks. Local users can exploit this by pre-creating symlinks with these names pointing to arbitrary files, causing cronic to overwrite the target files when it runs.
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
= 7.0= 8.0= 2= 42.1= 13.2CVSS 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
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- High
- Availability
- None
CVSS:3.0/AV:L/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 checksWork through these to decide whether this CVE applies to you.
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Check if cronic is installedRun 'which cronic' or 'dpkg -l | grep cronic' (Debian) or 'rpm -qa | grep cronic' (RPM-based)Affected if cronic is found on the system
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Determine cronic versionRun 'cronic --version' or check package version via dpkg/rpmAffected if Version is 2 or lower, or version cannot be determined (older package)
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Check if cronic is in useSearch for cronic calls in cron jobs, scripts, or systemd timers: 'grep -r cronic /etc/cron* /etc/systemd /opt /home'Affected if cronic is actively used to run scripts
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Verify /tmp permissionsRun 'ls -ld /tmp' to check for sticky-bit (mode 1777)Affected if /tmp lacks sticky-bit and system has untrusted local users
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Check for existing symlink attacksList files in /tmp matching cronic.out.*, cronic.err.*, cronic.trace.* patterns via 'ls -la /tmp/cronic*'Affected if Symlinks or files with these patterns already exist in /tmp
System is affected if cronic version 2 or lower is installed and actively used, especially in multi-user environments where /tmp lacks proper restrictions.
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 dataUpgrade to cronic version 3 or later which addresses the symlink vulnerability. If immediate upgrade is not feasible, ensure /tmp has restrictive sticky-bit permissions and avoid running cronic in multi-user untrusted environments.
Fix this in Debian Linux
Scoped from the published advisory
- Consultation1.0 h
- Implementation2.0 h
- Testing1.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,424.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2016-3992 — 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-2016-3992 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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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
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