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FirefoxWeb browser · Mozilla

CVE-2026-2760

CRITICAL · 10.0 CVSS v3.1 Published 2026-02-24
Fix available
A fix is available. Upgrade to 115.33.0 / 140.8.0 or later.
See remediation →
100/100
Remediation priority · Urgent
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
Sandbox escape due to incorrect boundary conditions in the Graphics: WebRender component. This vulnerability was fixed in Firefox 148, Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

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 exists in Mozilla's WebRender graphics component due to incorrect boundary conditions. This memory safety issue in the GPU-based rendering engine allows an attacker to bypass security sandbox restrictions, potentially executing arbitrary code with elevated privileges.

MitigationApply the vendor-supplied updates: Firefox 148 (or ESR 115.33/140.8), Thunderbird 148 (or 140.8) or later versions.

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:< 115.33.0< 148.0>= 128.0, < 140.8.0
ThunderbirdApplication
Affected:< 140.8.0< 148.0

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
Changed
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/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 Mozilla product
    Check if Firefox or Thunderbird is installed by looking for the application in the system (e.g., check for firefox or thunderbird executables, or open the application and look at Help > About)
    Affected if The system has Firefox or Thunderbird installed
  2. Determine Firefox version
    In Firefox, navigate to Help > About Firefox or enter 'about:support' in the address bar to view the version number
    Affected if Firefox version is less than 115.33.0, or is 128.0 or higher but less than 140.8.0, or is less than 148.0
  3. Determine Thunderbird version
    In Thunderbird, navigate to Help > About Thunderbird to view the version number
    Affected if Thunderbird version is less than 140.8.0 or less than 148.0
  4. Check if WebRender is enabled
    In the affected Firefox or Thunderbird, type 'about:config' in the address bar, search for 'gfx.webrender.enabled', and check its value (true means enabled)
    Affected if gfx.webrender.enabled is set to true (WebRender is active)
  5. Confirm vulnerable configuration
    If the product version falls within the affected ranges from steps 2 or 3 AND WebRender is enabled as confirmed in step 4, the environment is vulnerable to the sandbox escape
    Affected if Version is in affected range AND WebRender is enabled

The system is affected if it runs a vulnerable Firefox or Thunderbird version (pre-115.33.0, 128.0 to pre-140.8.0, or pre-148.0 for Firefox; pre-140.8.0 or pre-148.0 for Thunderbird) with WebRender graphics rendering enabled.

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 115.33.0 / 140.8.0 / 148.0 or later
Fixed in 115.33.0140.8.0148.0
Interim mitigation

Apply the vendor-supplied updates: Firefox 148 (or ESR 115.33/140.8), Thunderbird 148 (or 140.8) or later versions.

Recommended fix High confidence

Firefox 148 (standard release), Firefox ESR 115.33, or Firefox ESR 140.8; Thunderbird 148 or Thunderbird 140.8

  1. Open Firefox or Thunderbird and navigate to Menu > Help > About [Application Name] to check current version
  2. If prompted, click 'Update to [version]' to install the latest update automatically
  3. Alternatively, download the latest version from the official Mozilla website (www.mozilla.org) for your platform
  4. Restart the application after the update completes
  5. Verify the update by checking Menu > Help > About [Application Name] shows version 148 or ESR 115.33/140.8

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

Fix this in Firefox Scoped from the published advisory
  • Consultation1.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,040
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,664.

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-2026-2760 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