CVE-2015-4334
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 default configuration of SGOS in Blue Coat ProxySG before 6.2.16.5, 6.5 before 6.5.7.1, and 6.6 before 6.6.2.1 forwards authentication challenges from upstream origin content servers (OCS) when used in an explicit proxy deployment, which makes it easier for remote attackers to obtain sensitive information via a 407 (aka Proxy Authentication Required) HTTP status code, as demonstrated when using NTLM authentication.
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 confidenceBlue Coat ProxySG versions prior to 6.2.16.5, 6.5.7.1, and 6.6.2.1 have an insecure default configuration in explicit proxy deployments that forwards authentication challenge responses (407 status codes) from upstream origin content servers directly to clients, potentially leaking sensitive authentication information such as NTLM credentials or session data.
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>= 6.2, <= 6.2.16.4>= 6.5, <= 6.5.7.0>= 6.6, <= 6.6.2.0CVSS 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
- Partial
- Integrity
- None
- Availability
- None
AV:N/AC:L/Au:N/C:P/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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Identify ProxySG firmware versionAccess the ProxySG web UI and navigate to System > General > About, or use the CLI command 'show version' to display the installed firmware version.Affected if The displayed version falls within any of these ranges: 6.2.x through 6.2.16.4, 6.5.x through 6.5.7.0, or 6.6.x through 6.6.2.0.
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Confirm explicit proxy deployment modeIn the ProxySG web UI, go to Configuration > Proxy Services > Explicit Proxy, or use the CLI command 'show proxy-services explicit' to see if explicit proxy service is enabled.Affected if Explicit proxy mode is enabled and configured to forward requests to upstream origin content servers.
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Verify upstream authentication is configuredCheck proxy policy or authentication settings: in the web UI, go to Configuration > Authentication or Policy > Authentication. Look for any realm or authentication service configured to authenticate users to upstream origin servers.Affected if The proxy is configured to pass-through or forward authentication to origin content servers (upstream authentication).
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Inspect 407 response handling configurationReview proxy policy for any rules that explicitly handle 407 Proxy Authentication Required responses. Check under Policy > Visual Policy Manager > Response layers, or examine CPL (Content Policy Language) rules for 'response.status=407' handling.Affected if No policy rule exists to block, rewrite, or properly handle 407 responses from upstream servers before forwarding to clients.
You are affected if your ProxySG runs a vulnerable firmware version (pre-6.2.16.5, pre-6.5.7.1, or pre-6.6.2.1) AND is deployed in explicit proxy mode with upstream authentication configured, and 407 responses from origin servers are forwarded directly to clients without blocking or sanitization.
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 ProxySG to a patched version (6.2.16.5, 6.5.7.1, 6.6.2.1 or later) or modify the default configuration to block/handle 407 responses from upstream OCS appropriately in explicit proxy mode.
- Consultation2.0 h
- Implementation2.0 h
- Testing3.0 h
- Review / QA1.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2015-4334 — 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-2015-4334 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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