FirefoxWeb browser · Mozilla
CVE-2025-1018
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 · uneditedThe fullscreen notification is prematurely hidden when fullscreen is re-requested quickly by the user. This could have been leveraged to perform a potential spoofing attack. This vulnerability was fixed in Firefox 135 and Thunderbird 135.
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 confidenceIn Firefox and Thunderbird, the fullscreen notification (the indicator showing the user is in fullscreen mode) is prematurely hidden when fullscreen is re-requested quickly by the user. This timing issue in the UI state management allows an attacker to potentially spoof the user's perception of the fullscreen state, possibly concealing that fullscreen has been exited or misleading users about their current view mode.
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
< 135.0>= 131.0, < 135.0CVSS 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
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/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 checksWork through these to decide whether this CVE applies to you.
-
Check installed Firefox versionOpen Firefox, navigate to Menu > Help > About Firefox, or enter 'about:support' in the address bar and look at the Version fieldAffected if Version is less than 135.0 (e.g., 134.x, 133.x, etc.)
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Check installed Thunderbird versionOpen Thunderbird, go to Menu > Help > About Thunderbird, or enter 'about:support' in the address bar and look at the Version fieldAffected if Version is 131.0 or higher but less than 135.0 (e.g., 131.x, 132.x, 134.x)
If either Firefox or Thunderbird is installed in an affected version range, the fullscreen notification timing flaw is present in that installation.
Generated from the published advisory. Verify against your own configuration.
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 · scoped135.0
Upgrade to Firefox 135, Thunderbird 135, or later versions. These versions contain the fix that properly handles the fullscreen notification timing when fullscreen is re-requested quickly.
Firefox 135.0 or Thunderbird 135.0
- Back up critical data such as bookmarks, passwords, and email (for Thunderbird users) before proceeding
- Close all running instances of Firefox or Thunderbird
- Open Firefox or Thunderbird and navigate to Help > About Firefox (or About Thunderbird)
- Click 'Check for Updates' to trigger the built-in update mechanism
- Allow the update to download and install Firefox 135.0 or Thunderbird 135.0
- Restart the application after the update completes
- Confirm the fix by verifying the version in Help > About Firefox/Thunderbird shows version 135.0 or higher
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Firefox
Scoped from the published advisory
- Consultation1.0 h
- Testing1.0 h
- Review / QA1.0 h
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
Free · runs locallyCheck whether your project pulls in CVE-2025-1018 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2025-1018 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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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.
- 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