dbcve.org
FirefoxWeb browser · Mozilla

CVE-2025-4085

HIGH · 7.1 CVSS v3.1 Published 2025-04-29
Fix available
A fix is available. Upgrade to 138.0 or later.
See remediation →
77/100
Remediation priority · High
Remotely reachable 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
An attacker with control over a content process could potentially leverage the privileged UITour actor to leak sensitive information or escalate privileges. This vulnerability was fixed in Firefox 138 and Thunderbird 138.

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 privileged UITour actor in Firefox and Thunderbird can be exploited by an attacker who has control over a content process to leak sensitive information or escalate privileges. The UITour component, intended for user interface tour functionality, is accessible from content processes and can be abused to access privileged operations.

MitigationUpgrade to Firefox 138 or Thunderbird 138 or later to obtain the fixed UITour actor implementation.

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:< 138.0
ThunderbirdApplication
Affected:< 138.0

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
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/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
    Open Firefox, go to Help > About Firefox, or run 'firefox --version' from command line
    Affected if Version is displayed as less than 138.0 (e.g., 137.x, 136.x, etc.)
  2. Check installed Thunderbird version
    Open Thunderbird, go to Help > About Thunderbird, or run 'thunderbird --version' from command line
    Affected if Version is displayed as less than 138.0 (e.g., 137.x, 136.x, etc.)

If either Firefox or Thunderbird is installed with a version lower than 138.0, the environment is affected by this vulnerability.

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 138.0 or later
Fixed in 138.0
Interim mitigation

Upgrade to Firefox 138 or Thunderbird 138 or later to obtain the fixed UITour actor implementation.

Recommended fix High confidence

Firefox 138.0 and Thunderbird 138.0

  1. Close all running instances of Firefox and Thunderbird
  2. Download Firefox 138.0 (or later) from the official Mozilla website (www.mozilla.org/firefox)
  3. Run the Firefox installer and follow the prompts to complete the upgrade
  4. Download Thunderbird 138.0 (or later) from the official Mozilla website (www.mozilla.org/thunderbird)
  5. Run the Thunderbird installer and follow the prompts to complete the upgrade

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

Fix this in Firefox Scoped from the published advisory
  • Consultation2.0 h
  • Implementation1.0 h
  • Testing2.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,060
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,696.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2025-4085 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

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-2025-4085 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

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