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FirefoxWeb browser · Mozilla

CVE-2026-8945

HIGH · 7.5 CVSS v3.1 Published 2026-05-19
Fix available
A fix is available. Upgrade to 151.0 / 151.0.0 or later.
See remediation →
82/100
Remediation priority · High
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
Sandbox escape in Firefox and Firefox Focus for Android. This vulnerability was fixed in Firefox 151.

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 sandbox escape vulnerability in Firefox and Firefox Focus for Android allows an attacker to break out of the browser's security sandbox. The specific technical details of the escape mechanism are not disclosed in available documentation.

MitigationUpdate Firefox to version 151 or later, and ensure Firefox Focus for Android is updated to the corresponding fixed version.

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:< 151.0.0
Firefox FocusWeb browser
Affected:< 151.0

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

CVSS:3.1/AV:N/AC:H/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. Check Firefox desktop version
    Open Firefox and navigate to about:firefox in the address bar, or click Menu > Help > About Firefox
    Affected if The displayed version is below 151.0.0
  2. Check Firefox Focus for Android version
    Open the Google Play Store app, search for Firefox Focus, or go to your device's Settings > Apps > Firefox Focus to view the version information
    Affected if The displayed version is below 151.0

A user is affected if they have any installed version of Firefox below 151.0.0 or Firefox Focus for Android below 151.0, as these versions contain the sandbox escape 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 151.0 / 151.0.0 or later
Fixed in 151.0151.0.0
Interim mitigation

Update Firefox to version 151 or later, and ensure Firefox Focus for Android is updated to the corresponding fixed version.

Recommended fix High confidence

Firefox 151.0.0 (or later) / Firefox Focus 151.0 (or later)

  1. Open Firefox and navigate to Help > About Firefox (or go to about:support)
  2. Click 'Check for Updates' or wait for the automatic update check
  3. If an update is available, click 'Update to [version]'
  4. Restart Firefox after the update completes
  5. Verify the installed version is 151.0.0 or higher via Help > About Firefox
  6. For Firefox Focus on Android, open the Play Store, search for Firefox Focus, and update to version 151.0 or later
Caveat Review Firefox 151 release notes for any compatibility or feature changes before deploying

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

Fix this in Firefox Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing2.0 h
  • Review / QA1.0 h
9.0 hours of engineering $1,600
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,560.

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-2026-8945 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