FirefoxWeb browser · Mozilla
CVE-2010-4508
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 WebSockets implementation in Mozilla Firefox 4 through 4.0 Beta 7 does not properly perform proxy upgrade negotiation, which has unspecified impact and remote attack vectors, related to an "inherent problem" with the WebSocket specification.
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 WebSocket implementation in Firefox 4 through 4.0 Beta 7 fails to properly negotiate proxy upgrades during the WebSocket handshake. This allows remote attackers to exploit the connection upgrade process through proxies, potentially enabling cache poisoning, cross-site scripting, or man-in-the-middle attacks. The issue stems from an inherent problem in the WebSocket specification itself rather than just a Firefox implementation flaw.
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
FirefoxWeb browser
= 4.0CVSS 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
- Complete
- Integrity
- Complete
- Availability
- Complete
AV:N/AC:L/Au:N/C:C/I:C/A:C
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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Determine installed Firefox versionOpen Firefox, click Help > About Firefox, or navigate to about:support to view the version numberAffected if The version is 4.0 through 4.0 Beta 7 (any Firefox 4.x release)
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Check WebSocket configuration in about:configType about:config in the address bar, then search for 'websocket' to see if WebSocket is enabledAffected if The network.websocket.enabled preference is set to true (WebSocket is enabled)
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Identify proxy configurationGo to Firefox Options > Network Settings, or check system proxy settings. Note whether a proxy is configured (HTTP, SSL, or transparent proxy)Affected if A proxy server is configured in Firefox or at the system level and WebSocket is enabled
A user is affected if they are running Firefox 4.x (4.0 through 4.0 Beta 7) with WebSocket functionality enabled, particularly when operating behind a proxy.
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.
dbcve · scopedUpgrade to a modern Firefox version (current stable release) as Firefox 4 is obsolete and no longer supported. For legacy systems that cannot upgrade, disable WebSocket functionality or route traffic around transparent proxies.
Firefox 5.0 or later (the WebSocket implementation was updated in subsequent releases beyond 4.0)
- 1. Check the current Firefox version by navigating to 'about:support' in the address bar
- 2. If the version is 4.0 through 4.0 Beta 7, download and install Firefox 5.0 or later from the official Mozilla website (https://www.mozilla.org/firefox/)
- 3. After installation, verify the new version in 'about:support' to confirm the upgrade was successful
- 4. Test WebSocket functionality in your applications to ensure compatibility with the updated browser
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Firefox
Scoped from the published advisory
- Consultation1.0 h
- Implementation1.0 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 $1,200.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2010-4508 — 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-2010-4508 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