CVE-2017-12425
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 · uneditedAn issue was discovered in Varnish HTTP Cache 4.0.1 through 4.0.4, 4.1.0 through 4.1.7, 5.0.0, and 5.1.0 through 5.1.2. A wrong if statement in the varnishd source code means that particular invalid requests from the client can trigger an assert, related to an Integer Overflow. This causes the varnishd worker process to abort and restart, losing the cached contents in the process. An attacker can therefore crash the varnishd worker process on demand and effectively keep it from serving content - a Denial-of-Service attack. The specific source-code filename containing the incorrect statement varies across releases.
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 confidenceVarnish HTTP Cache contains an integer overflow vulnerability in varnishd where an incorrect if statement allows specific invalid client requests to trigger an assertion failure. This causes the worker process to abort and restart, resulting in loss of all cached content and enabling a denial-of-service attack.
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= 4.0.2= 4.0.3= 4.1.0= 4.0.1= 4.0.2= 4.0.3= 4.0.4= 5.0.0= 5.1.0= 5.1.1= 5.1.2= 4.1.0= 4.1.1= 4.1.2= 4.1.3= 4.1.4= 4.1.5= 4.1.6= 4.1.7CVSS 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:3.0/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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Identify installed Varnish versionRun `varnishd -V` or `varnishd -v` to display the varnishd version informationAffected if Version matches 4.0.1 through 4.0.4, 4.1.0 through 4.1.7, 5.0.0, or 5.1.0 through 5.1.2
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Verify varnishd process is runningRun `ps aux | grep varnishd` or `systemctl status varnish` to confirm the varnishd worker process is activeAffected if Varnishd is actively handling client requests
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Check if Varnish is exposed to untrusted clientsReview Varnish configuration file (default: /etc/varnish/default.vcl) and firewall rules to determine if Varnish listens on interfaces accessible from untrusted networksAffected if Varnish accepts connections from the internet or untrusted internal hosts without upstream filtering
You are affected if varnishd is running a version in the 4.0.x, 4.1.x, 5.0.x, or 5.1.x series AND the service is reachable by potential attackers sending malicious requests.
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 dataApply vendor patches for the affected versions (4.0.x, 4.1.x, 5.0.x, 5.1.x) or upgrade to a fixed version. Consider rate limiting or request validation at an upstream proxy while patching.
- Consultation4.0 h
- Implementation8.0 h
- Testing12.0 h
- Review / QA4.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2017-12425 — 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-2017-12425 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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