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FirefoxWeb browser · Mozilla

CVE-2026-12325

MEDIUM · 6.5 CVSS v3.1 Published 2026-06-16
Fix available
A fix is available. Upgrade to 115.37.0 / 140.12.0 or later.
See remediation →
72/100
Remediation priority · Elevated
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
Denial-of-service in the Graphics: ImageLib component. This vulnerability was fixed in Firefox 152, Firefox ESR 140.12, Firefox ESR 115.37, Thunderbird 152, and Thunderbird 140.12.

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 denial-of-service vulnerability exists in the Graphics: ImageLib component of Firefox and Thunderbird. The flaw allows attackers to cause the browser or email client to crash via specially crafted image files processed by the ImageLib library. Successful exploitation results in application termination rather than code execution.

MitigationUpgrade affected installations to Firefox 152 (or ESR 140.12/115.37 per branch) or Thunderbird 152 (or 140.12) to remediate the vulnerability. Organizations should inventory all deployed Firefox and Thunderbird instances and deploy the patched 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:< 115.37.0< 152.0.0>= 140.0, < 140.12.0
ThunderbirdApplication
Affected:< 152.0.0>= 140.0, < 140.12.0

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
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/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 installed version
    In Firefox, go to Menu > Help > About Firefox, or enter 'about:support' in the address bar. On Linux, run 'firefox --version' or check '/usr/lib/firefox/'. On Windows, check Add/Remove Programs or the executable properties.
    Affected if Version is below 115.37.0, OR between 140.0.0 and 140.11.0 inclusive, OR between 141.0.0 and 151.x.x (below 152.0.0)
  2. Check Thunderbird installed version
    In Thunderbird, go to Menu > Help > About Thunderbird. On Linux, run 'thunderbird --version'. On Windows, check Add/Remove Programs or the executable properties.
    Affected if Version is between 140.0.0 and 140.11.0 inclusive, OR below 152.0.0 (specifically versions 140.x through 151.x)
  3. Confirm ImageLib component is in use
    ImageLib is the internal graphics processing library used by Firefox and Thunderbird to decode and render image files. It is enabled by default for all image processing operations.
    Affected if This is a core component that processes images automatically - no configuration needed. If the application can load and display images, ImageLib is in use.

You are affected if you run Firefox below 115.37.0, Firefox 140.0-140.11.0, or any Firefox version from 140.x up to 151.x; or Thunderbird 140.0-140.11.0 or any Thunderbird version from 140.x up to 151.x.

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 115.37.0 / 140.12.0 / 152.0.0 or later
Fixed in 115.37.0140.12.0152.0.0
Interim mitigation

Upgrade affected installations to Firefox 152 (or ESR 140.12/115.37 per branch) or Thunderbird 152 (or 140.12) to remediate the vulnerability. Organizations should inventory all deployed Firefox and Thunderbird instances and deploy the patched versions.

Recommended fix High confidence

Firefox 152 (or ESR 115.37+ / ESR 140.12+); Thunderbird 152 (or 140.12+)

  1. Open Firefox or Thunderbird
  2. Click the menu button (three horizontal lines) and select 'Help'
  3. Select 'About Firefox' or 'About Thunderbird'
  4. The application will automatically check for updates
  5. If an update is available, click 'Update' or 'Restart to update'
  6. Wait for the update to download and install
  7. Restart the application

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-2026-12325 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