Ubuntu LinuxOperating system · Canonical
CVE-2016-4450
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 · uneditedos/unix/ngx_files.c in nginx before 1.10.1 and 1.11.x before 1.11.1 allows remote attackers to cause a denial of service (NULL pointer dereference and worker process crash) via a crafted request, involving writing a client request body to a temporary file.
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 NULL pointer dereference vulnerability in nginx os/unix/ngx_files.c allows remote attackers to crash the worker process via a crafted request that writes a client request body to a temporary file. The issue affects nginx versions before 1.10.1 and 1.11.x before 1.11.1.
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
Ubuntu LinuxOperating system
= 14.04= 15.10= 16.04
NginxWeb server / proxy
>= 1.3.9, < 1.10.1= 1.11.0
Debian LinuxOperating system
= 8.0CVSS 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
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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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Determine installed nginx versionRun `nginx -v` or `nginx -V` to see the exact version numberAffected if Version is before 1.10.1 or is 1.11.0 (1.11.x before 1.11.1)
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Check if client request body buffering to file is enabledInspect nginx configuration for `client_body_in_file_only` directive or large client_body_buffer_size values that may cause body buffering to diskAffected if `client_body_in_file_only on;` is set, or very large buffer sizes are configured that could trigger temp file creation
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Identify proxy or fastcgi pass configurations handling POST/PUT requestsReview nginx config for `proxy_pass` or `fastcgi_pass` blocks that handle file upload requests (POST/PUT methods)Affected if The server accepts large request bodies via proxy/fastcgi that could be written to temp files
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Verify temp file directory permissionsCheck that the nginx temp directory (typically /tmp or /var/tmp) is accessible and writable by the nginx worker processAffected if The worker process can write to a temp directory where client request bodies would be stored
You are affected if your nginx version is 1.10.0 or earlier, or 1.11.0, AND your configuration allows client request bodies to be written to temporary files (via client_body_in_file_only, large buffers, or proxy/fastcgi handling of large uploads).
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 data1.10.1
Upgrade nginx to version 1.10.1, 1.11.1, or later to patch the NULL pointer dereference in the file handling code.
Fix this in Ubuntu Linux
Scoped from the published advisory
- Consultation2.0 h
- Implementation2.0 h
- Testing2.0 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 $1,984.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2016-4450 — 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-2016-4450 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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