dbcve.org
SafariWeb browser · Apple

CVE-2021-30984

HIGH · 7.5 CVSS v3.1 Published 2021-08-24
Fix available
A fix is available. Upgrade to 8.3 / 12.1 or later.
See remediation →
82/100
Remediation priority · High
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 race condition was addressed with improved state handling. This issue is fixed in tvOS 15.2, macOS Monterey 12.1, Safari 15.2, iOS 15.2 and iPadOS 15.2, watchOS 8.3. Processing maliciously crafted web content may lead to arbitrary code execution.

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 race condition in WebKit (Safari's browser engine) allows processing of maliciously crafted web content to lead to arbitrary code execution. The vulnerability stems from improper state handling during web content processing, where concurrent operations can create a timing window that bypasses security checks.

MitigationApply the vendor-supplied security updates: iOS 15.2/iPadOS 15.2, macOS Monterey 12.1, Safari 15.2, tvOS 15.2, and watchOS 8.3.

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
SafariWeb browser
Affected:< 15.2
FedoraOperating system
Affected:= 34= 35
Debian LinuxOperating system
Affected:= 10.0= 11.0
IpadosOperating system
Affected:< 15.2
Iphone OsOperating system
Affected:< 15.2
macOSOperating system
Affected:< 12.1
TvosOperating system
Affected:< 15.2
WatchosOperating system
Affected:< 8.3

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
High
Privileges
None
User interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:H/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. Check Safari version on macOS
    Open Safari, click Safari menu > About Safari. Note the version number displayed.
    Affected if Version is earlier than 15.2 (e.g., 15.0, 15.1, or any 14.x/13.x release)
  2. Check iOS version on iPhone
    Open Settings > General > About. Note the version number next to 'Version'.
    Affected if Version is earlier than 15.2 (e.g., 15.0, 15.1, or any 14.x release)
  3. Check iPadOS version on iPad
    Open Settings > General > About. Note the version number next to 'Version'.
    Affected if Version is earlier than 15.2 (e.g., 15.0, 15.1, or any 14.x release)
  4. Check macOS version
    Click Apple menu > About This Mac. Note the version number (e.g., 12.0, 11.x, 10.x).
    Affected if macOS version is earlier than 12.1 (e.g., 12.0, 11.x, 10.x)
  5. Check tvOS version on Apple TV
    Go to Settings > General > About. Note the tvOS version displayed.
    Affected if Version is earlier than 15.2 (e.g., 15.0, 15.1, or any 14.x release)
  6. Check watchOS version on Apple Watch
    Open Watch app on iPhone, go to My Watch > General > About. Note the watchOS version.
    Affected if Version is earlier than 8.3 (e.g., 8.0, 7.x, 6.x)

You are affected if any Apple device (iPhone, iPad, Mac, Apple TV, Apple Watch) or Safari browser runs a version lower than the fixed releases AND uses WebKit to process untrusted web content.

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 8.3 / 12.1 / 15.2 or later
Fixed in 8.312.115.2
Interim mitigation

Apply the vendor-supplied security updates: iOS 15.2/iPadOS 15.2, macOS Monterey 12.1, Safari 15.2, tvOS 15.2, and watchOS 8.3.

Recommended fix High confidence

iOS 15.2, iPadOS 15.2, macOS Monterey 12.1, Safari 15.2, watchOS 8.3, tvOS 15.2

  1. Identify the affected Apple device or browser (iPhone, iPad, Mac, Apple Watch, Apple TV, or Safari)
  2. Check the current installed version of the operating system or browser
  3. For iOS devices: Navigate to Settings > General > Software Update and upgrade to iOS 15.2 or later
  4. For iPadOS devices: Navigate to Settings > General > Software Update and upgrade to iPadOS 15.2 or later
  5. For macOS: Navigate to System Preferences > Software Update and upgrade to macOS Monterey 12.1 or later
  6. For Safari: Safari 15.2 is included with macOS Monterey 12.1 and iOS 15.2/iPadOS 15.2; on older macOS, upgrade macOS to receive Safari 15.2
  7. For Apple Watch: Navigate to Settings > General > Software Update on the watch and upgrade to watchOS 8.3 or later
  8. For Apple TV: Navigate to Settings > System > Software Update and upgrade to tvOS 15.2 or later
Caveat Standard OS upgrade considerations apply - review app compatibility and back up data before upgrading

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Safari Scoped from the published advisory
  • Consultation1.0 h
  • Implementation2.0 h
  • Testing1.0 h
  • Review / QA1.0 h
5.0 hours of engineering $890
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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-2021-30984 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