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FirefoxWeb browser · Mozilla

CVE-2020-26965

MEDIUM · 6.5 CVSS v3.1 Published 2020-12-09
Fix available
A fix is available. Upgrade to 78.5 / 83.0 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
Some websites have a feature "Show Password" where clicking a button will change a password field into a textbook field, revealing the typed password. If, when using a software keyboard that remembers user input, a user typed their password and used that feature, the type of the password field was changed, resulting in a keyboard layout change and the possibility for the software keyboard to remember the typed password. This vulnerability affects Firefox < 83, Firefox ESR < 78.5, and Thunderbird < 78.5.

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

When using software keyboards that remember user input, clicking a 'Show Password' button changes the password field type from masked to visible. This field type change triggers a layout change in the software keyboard, causing it to potentially remember and store the typed password. This is a logic flaw where the visibility toggle inadvertently alters keyboard behavior that should remain consistent for security.

MitigationUpdate affected applications to Firefox 83+, Firefox ESR 78.5+, or Thunderbird 78.5+. For third-party applications, ensure the Show Password feature does not trigger keyboard layout changes or memory features when toggling field visibility.

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:< 83.0
Firefox EsrWeb browser
Affected:< 78.5
ThunderbirdApplication
Affected:< 78.5

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
None
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/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 the installed Mozilla product
    Open the application and navigate to Help > About (Firefox or Thunderbird) to reveal the exact version number
    Affected if The product is Firefox, Firefox ESR, or Thunderbird
  2. Check Firefox version
    Note the version number shown in the About dialog - compare it to the affected range of versions below 83.0
    Affected if Running Firefox version 82.x or earlier
  3. Check Firefox ESR version
    Note the version number shown in the About dialog - ESR versions display with 'ESR' label, compare to affected range below 78.5
    Affected if Running Firefox ESR version 78.4 or earlier
  4. Check Thunderbird version
    Open Thunderbird, go to Help > About to view the version - compare to affected range below 78.5
    Affected if Running Thunderbird version 78.4 or earlier
  5. Assess software keyboard usage
    Determine if a software keyboard (mobile keyboard, virtual keyboard, or third-party keyboard app with memory/prediction features) is in use, particularly on mobile devices or virtual desktop environments
    Affected if A software keyboard with memory or prediction capabilities is used alongside the affected application

You are affected if running Firefox below 83.0, Firefox ESR below 78.5, or Thunderbird below 78.5, AND using a software keyboard with memory or prediction features when the Show Password button is clicked.

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.

From vendor data
Upgrade available Upgrade to 78.5 / 83.0 or later
Fixed in 78.583.0
Interim mitigation

Update affected applications to Firefox 83+, Firefox ESR 78.5+, or Thunderbird 78.5+. For third-party applications, ensure the Show Password feature does not trigger keyboard layout changes or memory features when toggling field visibility.

Fix this in Firefox Scoped from the published advisory
  • Consultation2.0 h
  • Implementation8.0 h
  • Testing4.0 h
  • Review / QA2.0 h
16.0 hours of engineering $2,800
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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-2020-26965 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