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FirefoxWeb browser · Mozilla

CVE-2025-4088

MEDIUM · 6.5 CVSS v3.1 Published 2025-04-29
Fix available
A fix is available. Upgrade to 138.0 or later.
See remediation →
74/100
Remediation priority · Elevated
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
A security vulnerability in Thunderbird allowed malicious sites to use redirects to send credentialed requests to arbitrary endpoints on any site that had invoked the Storage Access API. This enabled potential Cross-Site Request Forgery attacks across origins. 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 · high confidence

This vulnerability in Thunderbird (and Firefox) allowed malicious websites to exploit the Storage Access API through redirects to send credentialed requests to arbitrary endpoints on any site that had invoked this API. This bypasses the intended same-origin protections and enables Cross-Site Request Forgery (CSRF) attacks across different origins.

MitigationUpgrade Thunderbird and Firefox installations to version 138 or later to remediate this vulnerability.

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

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/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 Firefox version
    Run 'firefox --version' in a terminal, or open Firefox and navigate to the URL 'about:support' to view the version listed in the Application Basics section
    Affected if The installed Firefox version is less than 138.0
  2. Check Thunderbird version
    Run 'thunderbird --version' in a terminal, or open Thunderbird and go to Help > About Thunderbird to see the version number
    Affected if The installed Thunderbird version is less than 138.0

If either Firefox or Thunderbird is installed with a version number below 138.0, the browser is vulnerable to this Storage Access API bypass that enables cross-origin CSRF attacks.

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 Thunderbird and Firefox installations to version 138 or later to remediate this vulnerability.

Recommended fix High confidence

Firefox 138.0+, Thunderbird 138.0+

  1. Upgrade Firefox to version 138.0 or later
  2. Upgrade Thunderbird to version 138.0 or later
  3. After upgrading, verify the installed version by navigating to about:Firefox (or Help > About Firefox) and about:Thunderbird (or Help > About Thunderbird)

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.

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-2025-4088 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