dbcve.org
FirefoxWeb browser · Mozilla

CVE-2024-8383

HIGH · 7.5 CVSS v3.1 Published 2024-09-03
Fix available
A fix is available. Upgrade to 115.15 / 128.2 or later.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click

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 · unedited
Firefox normally asks for confirmation before asking the operating system to find an application to handle a scheme that the browser does not support. It did not ask before doing so for the Usenet-related schemes news: and snews:. Since most operating systems don't have a trusted newsreader installed by default, an unscrupulous program that the user downloaded could register itself as a handler. The website that served the application download could then launch that application at will. This vulnerability affects Firefox < 130, Firefox ESR < 128.2, and Firefox ESR < 115.15.

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 confidence

Firefox fails to prompt for user confirmation before delegating unsupported URL schemes to the operating system. For the 'news:' and 'snews:' Usenet schemes specifically, Firefox bypasses the normal confirmation dialog, allowing malicious websites to silently launch externally downloaded applications registered as handlers without user consent.

MitigationUpdate Firefox to version 130 or later, or Firefox ESR to version 128.2/115.15 or later to receive the fix that restores the confirmation prompt before launching external applications for these schemes.

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
Affected:< 130.0
Firefox EsrWeb browser
Affected:< 115.15>= 128.0, < 128.2

CVSS 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
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/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 checks

Work through these to decide whether this CVE applies to you.

  1. Check installed Firefox version
    Navigate to about:support in Firefox or go to Menu > Help > About Firefox to see the version number
    Affected if Version is below 130.0 for standard Firefox, or below 128.2 (for 128.x branch) or below 115.15 (for 115.x ESR branch)
  2. Identify Firefox release channel
    In about:support, look at the 'Application Basics' section to see if you are using the Release, Beta, Dev, or ESR channel
    Affected if Using ESR channel with version less than 128.2 or less than 115.15, or using Release/Beta/Dev with version less than 130.0
  3. Check news: and snews: URL scheme handler configuration
    In the Firefox address bar, type about:config and search for 'network.protocol-handler.expose.news' and 'network.protocol-handler.expose.snews' preferences. Also check for 'network.protocol-handler.app.news' and 'network.protocol-handler.warn-scheme-news'
    Affected if network.protocol-handler.warn-scheme-news is set to false, or external application paths are configured in network.protocol-handler.app.news without a corresponding confirmation prompt setting set to true
  4. Verify external application handler registration
    Check the Windows Registry (HKCU\Software\Classes\news:) or macOS plist files for registered handlers for the 'news:' protocol, or examine any custom protocol handler configurations in Firefox's profile
    Affected if An external application is registered to handle 'news:' or 'snews:' URLs and Firefox does not show a confirmation dialog before launching it (the fix adds back the network.protocol-handler.warn-external.snews preference)

You are affected if your Firefox version is below 130.0 (Release/Beta/Dev) or below 128.2/115.15 (ESR) and you have an external application registered as a handler for the 'news:' or 'snews:' URL schemes without a confirmation prompt appearing.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 · scoped
Upgrade available Upgrade to 115.15 / 128.2 / 130.0 or later
Fixed in 115.15128.2130.0
Interim mitigation

Update Firefox to version 130 or later, or Firefox ESR to version 128.2/115.15 or later to receive the fix that restores the confirmation prompt before launching external applications for these schemes.

Recommended fix High confidence

Firefox 130.0+ or Firefox ESR 128.2+ (or Firefox ESR 115.15+)

  1. Open Firefox and click the menu button (three horizontal lines) in the top right corner
  2. Select 'Help' from the menu, then select 'About Firefox'
  3. The About Firefox window will open and automatically check for updates
  4. If an update is available, click 'Update to [version]' or wait for the download to complete
  5. Once the update is downloaded, click 'Restart to update Firefox' to apply the changes
  6. Alternatively, visit https://www.mozilla.org/firefox/download/ and download the latest version for your OS
Caveat Firefox upgrades typically have minimal breaking changes; however, some older extensions or themes may become incompatible with major version updates

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Firefox Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing1.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,090
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,744.

Scan for this in your stack

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2024-8383 in production — separate from our analysis above.

No notes yet

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What this is

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.

What belongs here
  • 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