CVE-2009-0804
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 · uneditedZiproxy 2.6.0, when transparent interception mode is enabled, uses the HTTP Host header to determine the remote endpoint, which allows remote attackers to bypass access controls for Flash, Java, Silverlight, and probably other technologies, and possibly communicate with restricted intranet sites, via a crafted web page that causes a client to send HTTP requests with a modified Host header.
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 confidenceZiproxy 2.6.0 in transparent interception mode uses the client-supplied HTTP Host header to determine the upstream destination server instead of validating against the intended target. This allows remote attackers to craft web pages that manipulate the Host header to route requests through the proxy to arbitrary internal or restricted network locations, bypassing access controls designed to block such communication.
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= 2.6.0CVSS 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
- High
- Authentication
- None
- Confidentiality
- Complete
- Integrity
- None
- Availability
- None
AV:N/AC:H/Au:N/C:C/I:N/A:N
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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Verify Ziproxy is installedCheck if Ziproxy is present on the system by running 'which ziproxy' or searching for the binary in common locations like /usr/sbin/ziproxy or /usr/local/sbin/ziproxyAffected if Ziproxy binary is not found on the system (not affected)
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Determine installed Ziproxy versionRun 'ziproxy -v' or 'ziproxy --version' to display the version numberAffected if Version is exactly 2.6.0 (vulnerable)
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Locate and review Ziproxy configuration fileFind the configuration file, typically at /etc/ziproxy/ziproxy.conf or /usr/local/etc/ziproxy.conf, and open it for inspectionAffected if Configuration file cannot be located or accessed
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Check if transparent interception mode is enabledIn the configuration file, search for directives related to transparent interception such as 'TransparentProxy', 'Transparent', or 'Intercept' - these indicate the mode is activeAffected if Transparent interception directives are present and enabled (potentially vulnerable if combined with CVE condition)
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Verify destination validation settingsIn the configuration file, look for directives like 'AllowConnect', 'Destinations', 'PermittedDestinations', or an allowlist configuration that validates upstream servers; also check if Host header validation is explicitly definedAffected if No destination validation or allowlist exists, and transparent interception mode is enabled (definitely affected)
You are affected if running Ziproxy version 2.6.0 with transparent interception mode enabled and without strict destination validation or Host header allowlisting in place.
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 dataDisable transparent interception mode or implement strict destination validation that ignores/validates the Host header against an allowlist of permitted upstream servers.
- Consultation3.0 h
- Implementation6.0 h
- Testing3.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,984.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2009-0804 — 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-2009-0804 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
- No weaponised exploit code, or anything meant to cause harm
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