CVE-2012-6687
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 · uneditedFastCGI (aka fcgi and libfcgi) 2.4.0 allows remote attackers to cause a denial of service (segmentation fault and crash) via a large number of connections.
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 confidenceFastCGI (libfcgi) 2.4.0 contains a vulnerability where handling a large number of connections can cause a segmentation fault and crash, resulting in denial of service. The issue appears to stem from improper resource management or lack of connection limits in the library.
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= 2.4.0CVSS 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
- Authentication
- None
- Confidentiality
- None
- Integrity
- None
- Availability
- Partial
AV:N/AC:L/Au:N/C:N/I:N/A:P
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 the installed libfcgi versionRun 'dpkg -l libfcgi*' on Debian-based systems, 'rpm -qa | grep -i fcgi' on RHEL-based systems, or check the library file directly with 'ldd --version' or look for libfcgi.so files and check their metadataAffected if The installed version is exactly 2.4.0
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Confirm the application uses FastCGIReview the web server configuration (Apache, Nginx, or other) to verify the application is configured to run via FastCGI (look for FastCGI directives, fcgiwrap, or mod_fcgid configurations)Affected if The application runs as a FastCGI process
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Check if the FastCGI endpoint is network-accessibleExamine the web server or FastCGI spawner configuration to determine if the FastCGI socket is bound to a network interface (TCP port) rather than only to a local Unix socketAffected if The FastCGI application accepts connections on a TCP port accessible to network clients
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Inspect application resource limitsCheck if the FastCGI application or spawner has explicit connection limits, worker process limits, or rate limiting configured (review init scripts, systemd unit files, or application-specific configuration)Affected if No connection or worker limits are defined and the application accepts external connections
If libfcgi version 2.4.0 is installed AND the FastCGI application accepts network connections without connection limits, the environment is vulnerable to the denial-of-service condition described in this CVE.
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 a patched version of libfcgi if available; otherwise, implement connection rate limiting at the application or network level to prevent resource exhaustion attacks.
- Consultation3.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2012-6687 — 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-2012-6687 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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