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FirefoxWeb browser · Mozilla

CVE-2025-9180

HIGH · 8.1 CVSS v3.1 Published 2025-08-19
Fix available
A fix is available. Upgrade to 115.27.0 / 128.14.0 or later.
See remediation →
88/100
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
Same-origin policy bypass in the Graphics: Canvas2D component. This vulnerability was fixed in Firefox 142, Firefox ESR 115.27, Firefox ESR 128.14, Firefox ESR 140.2, Thunderbird 142, Thunderbird 128.14, and Thunderbird 140.2.

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

A same-origin policy bypass in Firefox and Thunderbird's Canvas2D graphics component allows scripts from one origin to access canvas data from another origin that should be protected. This could enable attackers to exfiltrate sensitive data rendered on canvas elements, such as images from protected sources or data displayed in web applications.

MitigationUpdate affected installations to Firefox 142 or later, Firefox ESR 115.27/128.14/140.2 or later, or Thunderbird 142/128.14/140.2 or later. For organizations, deploy browser updates via standard patch management.

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:< 115.27.0< 142.0>= 128.0, < 128.14.0>= 140.0, < 140.2.0
ThunderbirdApplication
Affected:< 128.14.0< 142.0>= 140.0, < 140.2.0

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
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/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. Identify installed Firefox version
    Run 'firefox --version' on Linux/macOS, or check Help > About Firefox on Windows/Mac application
    Affected if Version is < 115.27.0, or >= 128.0 and < 128.14.0, or >= 140.0 and < 140.2.0, or >= 142.0 but < 142.0 (any version < 142.0 is affected)
  2. Identify installed Thunderbird version
    Run 'thunderbird --version' on Linux/macOS, or check Help > About Thunderbird on Windows/Mac application
    Affected if Version is < 128.14.0, or >= 140.0 and < 140.2.0, or >= 142.0 but < 142.0 (any version < 142.0 is affected)
  3. Verify Canvas2D component is present
    In Firefox, navigate to about:support and search for 'Canvas' in the Graphics section; the Canvas2D renderer should be listed as active
    Affected if Canvas2D is enabled (default state in all affected versions, no toggle exists to disable it)
  4. Confirm browser is used for rendering untrusted web content
    Review whether Firefox or Thunderbird is used to browse the internet or render HTML email content, which would allow same-origin script access to canvas data
    Affected if The browser handles web pages or HTML emails containing potentially malicious scripts that could exploit the Canvas2D same-origin bypass

A user is affected if they run any Firefox version below 142.0 or Thunderbird version below 142.0 (or the specific ESR versions listed), since the Canvas2D component is always enabled and cannot be disabled.

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 115.27.0 / 128.14.0 / 140.2.0 or later
Fixed in 115.27.0128.14.0140.2.0
Interim mitigation

Update affected installations to Firefox 142 or later, Firefox ESR 115.27/128.14/140.2 or later, or Thunderbird 142/128.14/140.2 or later. For organizations, deploy browser updates via standard patch management.

Recommended fix High confidence

Firefox 142, Firefox ESR 115.27, Firefox ESR 128.14, Firefox ESR 140.2, Thunderbird 142, Thunderbird 128.14, or Thunderbird 140.2 (depending on current release channel)

  1. Identify the currently installed Firefox or Thunderbird version via Help > About Firefox/Thunderbird
  2. For Firefox ESR 115.x users: Upgrade to Firefox ESR 115.27
  3. For Firefox ESR 128.x users: Upgrade to Firefox ESR 128.14
  4. For Firefox ESR 140.x users: Upgrade to Firefox ESR 140.2
  5. For Firefox main release users: Upgrade to Firefox 142
  6. For Thunderbird users on versions < 128.14.0: Upgrade to Thunderbird 128.14
  7. For Thunderbird users on versions >= 140.0, < 140.2.0: Upgrade to Thunderbird 140.2
  8. For Thunderbird users on versions < 142.0: Upgrade to Thunderbird 142
Caveat Users on extended support releases should plan to move to the next ESR branch; minor version upgrades typically have no breaking changes

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-2025-9180 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

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