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FirefoxWeb browser · Mozilla

CVE-2020-15661

MEDIUM · 6.5 CVSS v3.1 Published 2020-08-10
Fix available
A fix is available. Upgrade to 28.0 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
A rogue webpage could override the injected WKUserScript used by the logins autofill, this exploit could result in leaking a password for the current domain. This vulnerability affects Firefox for iOS < 28.

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 malicious webpage could override the WKUserScript injected by Firefox iOS for the login autofill feature, allowing the rogue script to intercept and exfiltrate stored passwords for the current domain. This is a script injection vulnerability in the iOS application's autofill mechanism.

MitigationUpgrade Firefox for iOS to version 28 or later to receive the patch that prevents rogue webpages from overriding the injected login autofill script.

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:< 28.0

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
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. Confirm you are using Firefox iOS
    Check the app name and platform - this vulnerability affects only Firefox for iOS, not Firefox for Android or desktop Firefox. Check your iOS device or the App Store listing.
    Affected if The device is running Firefox on iOS (iPhone or iPad).
  2. Check the Firefox iOS version
    Open the Firefox iOS app, tap the hamburger menu (three lines), go to Settings, then scroll to the bottom where the version number is displayed. Alternatively, check in the iOS App Store app listing.
    Affected if The version number is below 28.0 (for example, 27.5, 27.0, etc.).
  3. Check if password autofill is enabled
    On the iOS device, go to Settings > Passwords > Password Options. Verify whether 'AutoFill Passwords' is turned on and whether Firefox iOS is allowed to autofill passwords.
    Affected if AutoFill Passwords is enabled and Firefox iOS has permission to autofill passwords.

You are affected if you are running Firefox for iOS with a version lower than 28.0 and have password autofill enabled for the app.

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 28.0 or later
Fixed in 28.0
Interim mitigation

Upgrade Firefox for iOS to version 28 or later to receive the patch that prevents rogue webpages from overriding the injected login autofill script.

Fix this in Firefox Scoped from the published advisory
  • Consultation1.0 h
  • Implementation1.0 h
  • Testing2.0 h
  • Review / QA1.0 h
5.0 hours of engineering $860
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,376.

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-2020-15661 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