CVE-1999-0420
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 · uneditedumapfs allows local users to gain root privileges by changing their uid through a malicious mount_umap program.
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 confidenceumapfs contains a privilege escalation vulnerability where local users can gain root privileges by manipulating their UID through a malicious mount_umap program. The mount_umap binary likely lacks proper validation to ensure only privileged users can change UID mappings, allowing unprivileged local users to escalate to root.
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 dataall versionsCVSS 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
- Authentication
- None
- Confidentiality
- Complete
- Integrity
- Complete
- Availability
- Complete
AV:L/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 checksWork through these to decide whether this CVE applies to you.
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Check if umapfs package is installedRun 'pkg_info | grep umapfs' or 'pkginfo -a | grep umapfs' on NetBSD to list installed umapfs packagesAffected if Any umapfs package or component is listed in the installed packages
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Locate the mount_umap binaryRun 'which mount_umap' or 'find /usr -name mount_umap -type f 2>/dev/null' to find the mount_umap binary pathAffected if The mount_umap binary exists on the system at any location
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Verify mount_umap permissionsRun 'ls -la /path/to/mount_umap' (using the path found above) to check owner, group, and permission bitsAffected if The binary is owned by a non-root user, group writable, or world-executable, or if it lacks the setuid bit when it should have one for proper operation
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Check for active umapfs mountsRun 'mount | grep umapfs' or check /proc/mounts (if available) for any active umapfs mountsAffected if There are any active umapfs mounts on the system
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Check for setuid on mount_umap binaryRun 'ls -la /path/to/mount_umap' and look for 's' in the owner execute field indicating setuid bitAffected if The mount_umap binary has the setuid bit set (which would allow any user to run it and potentially exploit the UID mapping flaw)
A user is affected if the umapfs package is installed and the mount_umap binary exists with permissive permissions or setuid bit, allowing unprivileged UID manipulation.
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 dataRemove umapfs and its mount_umap binary if not required, or restrict execution to root-only with proper file permissions. Consider migrating to alternative user-space filesystem solutions with better security models.
- Consultation1.0 h
- Implementation1.0 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 $1,200.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-1999-0420 — 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-1999-0420 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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