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FirefoxWeb browser · Mozilla

CVE-2022-46874

HIGH · 8.8 CVSS v3.1 Published 2022-12-22
Fix available
A fix is available. Upgrade to 102.6 / 108.0 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 file with a long filename could have had its filename truncated to remove the valid extension, leaving a malicious extension in its place. This could potentially led to user confusion and the execution of malicious code.<br/>*Note*: This issue was originally included in the advisories for Thunderbird 102.6, but a patch (specific to Thunderbird) was omitted, resulting in it actually being fixed in Thunderbird 102.6.1. This vulnerability affects Firefox < 108, Thunderbird < 102.6.1, Thunderbird < 102.6, and Firefox ESR < 102.6.

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 filename truncation vulnerability in Firefox and Thunderbird causes long filenames to have their valid extensions incorrectly removed during processing, leaving a potentially malicious extension visible to users. This can trick users into executing malicious files they believe to be safe documents.

MitigationUpdate affected installations to Firefox 108+, Thunderbird 102.6.1+, or Firefox ESR 102.6+ to obtain the vendor patch that correctly handles filename truncation.

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:< 108.0
Firefox EsrWeb browser
Affected:< 102.6
ThunderbirdApplication
Affected:< 102.6

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 Mozilla product
    Check for Firefox or Thunderbird installation: On Windows, look in Program Files for 'Mozilla Firefox' or 'Mozilla Thunderbird' folders. On macOS, check /Applications for Firefox.app or Thunderbird.app. On Linux, run 'which firefox thunderbird' or check /usr/lib/firefox or /usr/lib/thunderbird directories.
    Affected if Either Firefox or Thunderbird is installed on the system
  2. Determine Firefox version
    For Firefox: Click menu > Help > About Firefox, or run 'firefox --version' from command line. On Windows, check the executable properties or the updates.ini file in the installation directory.
    Affected if Firefox version is below 108.0 (or below 102.6 for ESR releases)
  3. Determine Thunderbird version
    For Thunderbird: Click menu > Help > About Thunderbird, or run 'thunderbird --version' from command line. On Windows, check the executable properties.
    Affected if Thunderbird version is below 102.6
  4. Confirm vulnerability trigger condition
    The vulnerability affects file downloads/attachments with long filenames where the extension could be obscured. Check if users process external files through the mail client (Thunderbird) or download files through the browser (Firefox).
    Affected if Users receive or download files with long filenames through the affected application, and the application misprocesses the filename extension during handling

A user is affected if Firefox (any channel < 108.0), Firefox ESR (< 102.6), or Thunderbird (< 102.6) is installed and the application processes file attachments or downloads with long filenames where the extension could be misrepresented.

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 102.6 / 108.0 or later
Fixed in 102.6108.0
Interim mitigation

Update affected installations to Firefox 108+, Thunderbird 102.6.1+, or Firefox ESR 102.6+ to obtain the vendor patch that correctly handles filename truncation.

Recommended fix High confidence

Firefox 108.0+, Firefox ESR 102.6+, or Thunderbird 102.6.1+

  1. 1. Determine which Mozilla product is affected (Firefox, Firefox ESR, or Thunderbird)
  2. 2. Close the affected application completely
  3. 3. For Firefox: Navigate to the official Mozilla download page at www.mozilla.org or use the application's built-in update mechanism (Help > About Firefox > Check for Updates)
  4. 4. For Thunderbird: Navigate to www.mozilla.org or use Help > About Thunderbird > Check for Updates
  5. 5. Download and install the appropriate fixed version: Firefox 108.0 or later, Firefox ESR 102.6 or later, or Thunderbird 102.6.1 or later
  6. 6. Restart the application after installation
  7. 7. Verify the installed version by checking Help > About to confirm the version number matches or exceeds the fixed release
Caveat Standard security update with minimal risk of breaking changes; users should always update to latest stable release

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
  • Testing2.0 h
  • Review / QA1.0 h
7.0 hours of engineering $1,240
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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-2022-46874 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