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FirefoxWeb browser · Mozilla

CVE-2025-1011

HIGH · 8.8 CVSS v3.1 Published 2025-02-04
Fix available
A fix is available. Upgrade to 128.7.0 / 135.0 or later.
See remediation →
95/100
Remediation priority · Urgent
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
A bug in WebAssembly code generation could have lead to a crash. It may have been possible for an attacker to leverage this to achieve code execution. This vulnerability was fixed in Firefox 135, Firefox ESR 128.7, Thunderbird 128.7, 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 · moderate confidence

A bug in Mozilla's WebAssembly code generation can cause a crash and potentially allow an attacker to achieve arbitrary code execution through specially crafted WebAssembly code. The vulnerability exists in the WASM compiler's code generation phase.

MitigationUpdate affected Mozilla products (Firefox to version 135+, Firefox ESR to 128.7+, Thunderbird to 128.7+ or 135+) 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:< 128.7.0< 135.0
ThunderbirdApplication
Affected:< 135.0>= 128.0.1, < 128.7.0

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
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/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. Identify installed Firefox version
    Open Firefox, go to Menu > Help > About Firefox, or run 'firefox --version' in terminal
    Affected if version is below 128.7.0 or between 128.7.0 and 134.x inclusive
  2. Identify installed Thunderbird version
    Open Thunderbird, go to Menu > Help > About Thunderbird, or run 'thunderbird --version' in terminal
    Affected if version is 128.0.1 or above but below 128.7.0, or below 135.0
  3. Check if WebAssembly is enabled in Firefox
    In Firefox address bar, enter 'about:config', search for 'javascript.options.wasm', confirm the value is true (default)
    Affected if WebAssembly is enabled (default state) - the vulnerability exists in the Wasm JIT compilation pipeline
  4. Verify browser is not a patched version
    Compare your exact version number against the fixed releases: Firefox 135.0, Firefox ESR 128.7.0, Thunderbird 128.7.0, Thunderbird 135.0
    Affected if your version does not match any of these fixed versions

You are affected if you run Firefox below 135.0 or Thunderbird below 135.0 (specifically 128.0.1 to 128.7.0 range) with WebAssembly enabled (the default configuration).

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 128.7.0 / 135.0 or later
Fixed in 128.7.0135.0
Interim mitigation

Update affected Mozilla products (Firefox to version 135+, Firefox ESR to 128.7+, Thunderbird to 128.7+ or 135+) to remediate this vulnerability.

Recommended fix High confidence

Firefox 135.0 (or Firefox ESR 128.7.0); Thunderbird 135.0 or 128.7.0

  1. 1. Determine your current Firefox or Thunderbird version by clicking the menu button (three horizontal lines) and selecting 'Help' > 'About Firefox' or 'About Thunderbird'
  2. 2. For Firefox users: If your version is below 135.0, download Firefox 135.0 from the official Mozilla website at www.mozilla.org/firefox/
  3. 3. For Firefox ESR users: If your version is below 128.7.0, download Firefox ESR 128.7.0 from www.mozilla.org/firefox/enterprise/
  4. 4. For Thunderbird users: If your version is below 135.0 (or between 128.0.1 and 128.7.0), download Thunderbird 135.0 or 128.7.0 from www.mozilla.org/thunderbird/
  5. 5. Close the application completely before installing the update
  6. 6. Run the downloaded installer and follow the prompts to install the fixed version
  7. 7. Restart the application after installation completes
  8. 8. Verify the fix by checking 'About' again to confirm you are running version 135.0, 128.7.0, or higher
Caveat Standard Firefox/Thunderbird updates typically maintain settings and extensions, though some legacy add-ons may require updates or become incompatible

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

Fix this in Firefox Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing1.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,090
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,744.

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-2025-1011 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