FirefoxWeb browser · Mozilla
CVE-2025-8029
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 · uneditedThunderbird executed `javascript:` URLs when used in `object` and `embed` tags. This vulnerability was fixed in Firefox 141, Firefox ESR 128.13, Firefox ESR 140.1, Thunderbird 141, Thunderbird 128.13, and Thunderbird 140.1.
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 confidenceThunderbird incorrectly executed javascript: URLs when they were embedded in HTML object and embed tags, allowing script execution in the context of the page. This is a cross-site scripting (XSS) vulnerability specific to how Thunderbird handled these specific HTML elements.
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
< 128.13.0< 141.0>= 140.0, < 140.1.0< 128.13.0< 141.0>= 140.0, < 140.1.0CVSS 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
- 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 checksWork through these to decide whether this CVE applies to you.
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Confirm Thunderbird is installedCheck for Thunderbird in your applications or program files directory, or run 'thunderbird --version' from command lineAffected if Thunderbird is present on the system
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Identify installed Thunderbird versionOpen Thunderbird, go to Help > About Thunderbird, or run 'thunderbird --version' in terminalAffected if The version displayed is < 128.13.0, OR >= 140.0 and < 140.1.0
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Verify the vulnerability attack surfaceThis vulnerability requires HTML object or embed tags containing javascript: URLs to be processed by Thunderbird (e.g., viewing an HTML email or web page with such content)Affected if Thunderbird with a vulnerable version processes HTML content containing javascript: URLs in object or embed tags
You are affected if Thunderbird is installed and its version falls within < 128.13.0, or >= 140.0 but < 140.1.0.
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 · scoped128.13.0140.1.0141.0
Upgrade Thunderbird to version 141, 128.13, or 140.1 (or later) to obtain the security patch that prevents javascript: URL execution in object and embed tags.
Firefox 141 / Firefox ESR 128.13 / Firefox ESR 140.1 / Thunderbird 141 / Thunderbird ESR 128.13 / Thunderbird ESR 140.1
- 1. Identify the current Firefox and/or Thunderbird version by navigating to Help > About (or equivalent menu)
- 2. For Firefox users: Upgrade to Firefox 141.0 or later for mainstream releases, or Firefox ESR 128.13 / ESR 140.1 depending on your ESR branch
- 3. For Thunderbird users: Upgrade to Thunderbird 141.0 or later, or Thunderbird ESR 128.13 / ESR 140.1 depending on your ESR branch
- 4. Verify the upgrade was successful by checking Help > About shows version 141.0, 128.13, or 140.1 or later
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Firefox
Scoped from the published advisory
- Consultation2.0 h
- Implementation1.0 h
- Testing2.0 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 $1,696.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2025-8029 — 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-2025-8029 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
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