CVE-1999-0440
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 · uneditedThe byte code verifier component of the Java Virtual Machine (JVM) allows remote execution through malicious web pages.
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 confidenceThe byte code verifier component of the Java Virtual Machine (JVM) contained a flaw that allowed malicious Java applets to bypass security checks and execute arbitrary code on victim machines through specially crafted web pages.
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= 4.5= 4.0= 4.01= 4.02= 4.03= 4.04= 4.05= 4.5= 4.06= 4.07= 4.08= 4.61all 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
- Network
- Complexity
- Low
- Authentication
- None
- Confidentiality
- Partial
- Integrity
- Partial
- Availability
- Partial
AV:N/AC:L/Au:N/C:P/I:P/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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Check for Netscape Navigator installationSearch for netscape.exe or check registry for Netscape Navigator installation under common program paths (C:\Program Files\Netscape or similar)Affected if Netscape Navigator version 4.0 through 4.61 is installed
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Check for Netscape Communicator installationSearch for communicator.exe or check registry for Netscape Communicator installationAffected if Netscape Communicator version 4.5 is installed
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Check for Sun Java/JVM installationSearch for java.exe, javaw.exe, or JVM-related files in system directories (C:\Windows\System, C:\Program Files\Java) or check registry for JavaSoft entryAffected if Any version of Sun Java or JVM is installed on the system
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Verify Java browser plugin is enabledFor Netscape browsers, check the browser configuration or plugins directory for Java plugin (npjava*.dll or similar) and confirm it is not disabledAffected if The Java browser plugin is enabled in Netscape and loads Java applets from web pages
A system is affected if Netscape Navigator (any version 4.0-4.61), Netscape Communicator 4.5, or Sun Java/JVM is installed with the Java browser plugin enabled, as the byte code verifier flaw can be exploited through specially crafted Java applets loaded via web pages.
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 dataUpdate the JVM to a patched version that addresses this vulnerability, or disable the Java browser plugin/applet functionality to prevent exploitation via web pages.
- 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-1999-0440 — 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-1999-0440 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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A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.
- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
- No spam, self-promotion, credentials, or personal data