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FirefoxWeb browser · Mozilla

CVE-2025-14328

HIGH · 8.8 CVSS v3.1 Published 2025-12-09
Fix available
A fix is available. Upgrade to 140.6.0 / 146.0 or later.
See remediation →
95/100
Remediation priority · Urgent
Remotely reachable No privileges

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
Privilege escalation in the Netmonitor component. This vulnerability was fixed in Firefox 146, Firefox ESR 140.6, Thunderbird 146, and Thunderbird 140.6.

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 confidence

A privilege escalation vulnerability exists in the Netmonitor component of Firefox, Firefox ESR, and Thunderbird. Netmonitor is the developer tool for inspecting network requests and responses. The vulnerability allows a user to gain elevated privileges beyond their intended access level, potentially enabling unauthorized access to sensitive network data or actions. This was patched in Firefox 146, Firefox ESR 140.6, Thunderbird 146, and Thunderbird 140.6.

MitigationUpgrade to Firefox 146+, Firefox ESR 140.6+, Thunderbird 146+, or Thunderbird 140.6+ to remediate this vulnerability. No additional configuration or code changes are required.

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:< 140.6.0< 146.0
ThunderbirdApplication
Affected:< 140.6.0< 146.0

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
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

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. Identify installed Firefox version
    Open Firefox, click Help > About Firefox, or navigate to about:support in the address bar. Note the version number displayed.
    Affected if The version shown is less than 140.6.0, or is 140.6.0 through 145.x (non-ESR versions below 146.0)
  2. Identify installed Thunderbird version
    Open Thunderbird, click Help > About Thunderbird. Note the version number displayed.
    Affected if The version shown is less than 140.6.0, or is 140.6.0 through 145.x (versions below 146.0)
  3. Check if Firefox ESR version
    In the About Firefox window, look for 'ESR' in the version string. Alternatively, navigate to about:support and look for the 'Application Basics' section which lists the version and channel.
    Affected if Running Firefox ESR versions below 140.6.0
  4. Determine if Netmonitor is used
    Open Developer Tools by pressing F12 or Ctrl+Shift+I, then click the Network tab (Netmonitor). This confirms the vulnerable component is accessible.
    Affected if The Netmonitor/Network tab in Developer Tools is accessible and functional on the affected version

You are affected if you are running any version of Firefox, Firefox ESR, or Thunderbird below 140.6.0, or non-ESR Firefox/Thunderbird versions between 140.6.0 and 145.x, and you have access to or use the Developer Tools Netmonitor feature.

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 140.6.0 / 146.0 or later
Fixed in 140.6.0146.0
Interim mitigation

Upgrade to Firefox 146+, Firefox ESR 140.6+, Thunderbird 146+, or Thunderbird 140.6+ to remediate this vulnerability. No additional configuration or code changes are required.

Recommended fix High confidence

Firefox 146.0+ (standard) or Firefox ESR 140.6+ (ESR); Thunderbird 146.0+ (standard) or Thunderbird ESR 140.6+ (ESR)

  1. 1. Check the currently installed Firefox or Thunderbird version by navigating to the application menu > Help > About (or typing 'about:support' in the address bar)
  2. 2. If using Firefox: Upgrade to version 146.0 or later for standard releases, or upgrade to Firefox ESR 140.6 or later if using the ESR channel
  3. 3. If using Thunderbird: Upgrade to version 146.0 or later for standard releases, or upgrade to Thunderbird ESR 140.6 or later if using the ESR channel
  4. 4. Restart the application after the update completes
  5. 5. Verify the version has been updated by checking Help > About to confirm the installed version is at or above the fixed release

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
4.0 hours of engineering $750
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,200.

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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-2025-14328 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