CVE-2009-2069
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 · uneditedMicrosoft Internet Explorer before 8 displays a cached certificate for a (1) 4xx or (2) 5xx CONNECT response page returned by a proxy server, which allows man-in-the-middle attackers to spoof an arbitrary https site by letting a browser obtain a valid certificate from this site during one request, and then sending the browser a crafted 502 response page upon a subsequent request.
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 confidenceInternet Explorer before version 8 incorrectly displays cached SSL certificates from successful CONNECT requests when rendering proxy error pages (4xx/5xx responses). An attacker can exploit this by first triggering a legitimate HTTPS connection to populate the certificate cache, then sending a crafted 502 error response - the browser displays the previously cached valid certificate, spoofing a legitimate HTTPS site.
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= 5.0= 5.22= 6.0= 3.0= 3.0.1= 3.0.2= 3.1= 3.2= 4.0= 4.0.1= 4.01= 4.1= 4.5= 4.40.308= 4.40.520CVSS 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
- M
- Authentication
- None
- Confidentiality
- Partial
- Integrity
- Partial
- Availability
- None
AV:N/AC:M/Au:N/C:P/I:P/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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Check Internet Explorer versionOpen Internet Explorer, click Help > About Internet Explorer (or access the About dialog via the menu bar). Note the version number displayed.Affected if The version is earlier than 8.0 (for example, 5.0, 5.22, 6.0, or versions 3.x, 4.x as listed in the affected versions).
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Verify proxy configuration is enabledIn Internet Explorer, go to Tools > Internet Options > Connections > LAN settings. Check if 'Use a proxy server for your LAN' is enabled, or check for configured proxy auto-configuration (PAC) scripts.Affected if A proxy is configured - the vulnerability only applies when IE is using a proxy and receives proxy error responses (4xx/5xx).
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Confirm IE is used as the browserIdentify if Internet Explorer is the active browser in use. Check running processes (iexplore.exe) or default browser settings.Affected if Internet Explorer is actively being used - the vulnerability is specific to the IE browser engine.
You are affected if you are running any Internet Explorer version earlier than 8.0 with a proxy configured, as the browser will incorrectly display cached SSL certificates from prior successful CONNECT requests when rendering proxy error 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 dataUpgrade to Internet Explorer 8 or later, or migrate to a modern browser (Chrome, Firefox, Edge) that does not exhibit this certificate caching behavior.
- Consultation1.0 h
- Implementation2.0 h
- Testing1.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2009-2069 — 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-2009-2069 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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