dbcve.org
FedoraOperating system · Fedoraproject

CVE-2021-1801

MEDIUM · 6.5 CVSS v3.1 Published 2021-04-02
Fix available
A fix is available. Upgrade to 2.30.6 / 7.3 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
This issue was addressed with improved iframe sandbox enforcement. This issue is fixed in macOS Big Sur 11.2, Security Update 2021-001 Catalina, Security Update 2021-001 Mojave, watchOS 7.3, tvOS 14.4, iOS 14.4 and iPadOS 14.4. Maliciously crafted web content may violate iframe sandboxing policy.

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

CVE-2021-1801 is a sandbox bypass vulnerability in Apple's WebKit where maliciously crafted web content can violate iframe sandboxing policy. The issue stems from insufficient enforcement of the sandbox attribute on iframes, potentially allowing cross-origin attacks such as script execution in unintended contexts, data theft, or navigation manipulation.

MitigationApply the available security updates for affected Apple products (macOS Big Sur 11.2+, Security Update 2021-001 for Catalina/Mojave, watchOS 7.3, tvOS 14.4, iOS/iPadOS 14.4). For web applications, implement Content-Security-Policy headers as an additional defense-in-depth measure.

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
FedoraOperating system
Affected:= 32= 33
Ipad OsOperating system
Affected:< 14.4
Iphone OsOperating system
Affected:< 14.4
macOSOperating system
Affected:>= 11.0.1, < 11.2
TvosOperating system
Affected:< 14.4
WatchosOperating system
Affected:< 7.3
WebkitgtkWeb browser
Affected:< 2.30.6

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
None
Integrity
High
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/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 checks

Work through these to decide whether this CVE applies to you.

  1. Identify the operating system product
    Determine if the system runs one of the affected Apple operating systems (macOS, iOS, iPadOS, tvOS, watchOS) or Fedora, or uses WebKitGTK for web rendering
    Affected if The system runs any of the listed affected products and versions
  2. Check macOS version
    Run 'sw_vers -productVersion' in Terminal to obtain the macOS version number
    Affected if The version is 11.0.1, 11.1, or 11.2 (the affected range >= 11.0.1, < 11.2)
  3. Check iOS or iPadOS version
    Go to Settings > General > About on the device and note the version number, or use an MDM or device management tool
    Affected if The version is earlier than 14.4 (any version < 14.4)
  4. Check tvOS or watchOS version
    On Apple TV, go to Settings > General > About > Version. On Apple Watch, open the Watch app on iPhone and go to General > About
    Affected if tvOS is earlier than 14.4 or watchOS is earlier than 7.3
  5. Check WebKitGTK version on Fedora
    Run 'rpm -qa webkit2gtk' or 'rpm -qa webkitgtk' to list the installed WebKitGTK package version
    Affected if The installed version is earlier than 2.30.6 (any version < 2.30.6)
  6. Verify web content rendering with iframes
    Inspect web applications or hosted content for the presence of iframe elements with the sandbox attribute, as the vulnerability only affects environments that render sandboxed web content
    Affected if The environment serves or renders web pages containing sandboxed iframes using the affected WebKit version

The environment is affected if it runs any of the listed products at the specified vulnerable versions and renders web content with sandboxed iframes.

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 2.30.6 / 7.3 / 11.2 or later
Fixed in 2.30.67.311.2
Interim mitigation

Apply the available security updates for affected Apple products (macOS Big Sur 11.2+, Security Update 2021-001 for Catalina/Mojave, watchOS 7.3, tvOS 14.4, iOS/iPadOS 14.4). For web applications, implement Content-Security-Policy headers as an additional defense-in-depth measure.

Fix this in Fedora Scoped from the published advisory
  • Consultation1.0 h
  • Testing1.0 h
  • Review / QA1.0 h
3.0 hours of engineering $750
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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-2021-1801 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