dbcve.org
SafariWeb browser · Apple

CVE-2021-30846

HIGH · 7.8 CVSS v3.1 Published 2021-10-19
Fix available
A fix is available. Upgrade to 8.0 / 12.0.1 or later.
See remediation →
81/100
Remediation priority · High
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 memory corruption issue was addressed with improved memory handling. This issue is fixed in iOS 14.8 and iPadOS 14.8, Safari 15, tvOS 15, iOS 15 and iPadOS 15, watchOS 8. 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

This is a memory corruption vulnerability in Apple's WebKit rendering engine affecting Safari and web content processing in iOS, iPadOS, tvOS, and watchOS. The vulnerability allows arbitrary code execution when a user processes maliciously crafted web content, likely through a use-after-free or similar memory management flaw.

MitigationApply the vendor-supplied updates: iOS 14.8/iPadOS 14.8, iOS 15/iPadOS 15, Safari 15, tvOS 15, or watchOS 8 depending on the affected device. Prioritize updating mobile devices and any systems with direct internet exposure.

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:< 15.0
Debian LinuxOperating system
Affected:= 10.0= 11.0
FedoraOperating system
Affected:= 33= 34
IpadosOperating system
Affected:< 14.8
Iphone OsOperating system
Affected:< 14.8
macOSOperating system
Affected:< 12.0.1
TvosOperating system
Affected:< 15.0
WatchosOperating system
Affected:< 8.0

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
Local
Complexity
Low
Privileges
None
User interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/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. Determine the product and platform
    Identify whether the system runs macOS, iOS, iPadOS, tvOS, watchOS, Debian Linux, or Fedora Linux. On Apple devices, go to Settings > General > About. On Linux systems, run 'uname -a' or check /etc/os-release.
    Affected if The system runs any of the affected products listed in the CVE (Safari, iOS, iPadOS, tvOS, watchOS, Debian 10/11, Fedora 33/34).
  2. Check the installed Safari version on macOS
    Open Safari, click Safari menu > About Safari. Compare the version number to 15.0.
    Affected if Safari version is lower than 15.0.
  3. Check the iOS or iPadOS version
    Go to Settings > General > About on the iPhone or iPad. Note the version number.
    Affected if iOS or iPadOS version is lower than 14.8.
  4. Check the macOS version
    Go to Apple menu > About This Mac. Note the version number.
    Affected if macOS version is lower than 12.0.1.
  5. Check the tvOS or watchOS version
    On Apple TV: go to Settings > General > About. On Apple Watch: open the Watch app on iPhone > General > About.
    Affected if tvOS is lower than 15.0 or watchOS is lower than 8.0.
  6. Check WebKit package version on Debian or Fedora Linux
    On Debian: run 'dpkg -l | grep webkit' or 'apt show libwebkit2gtk-4.0-37'. On Fedora: run 'rpm -qa | grep webkit'. Compare the installed version to the affected package versions in the distribution repositories.
    Affected if The WebKit package version corresponds to the vulnerable versions shipped with Debian 10.0, 11.0, Fedora 33, or Fedora 34.

A user is affected if their Safari is below 15.0, iOS/iPadOS is below 14.8, macOS is below 12.0.1, tvOS is below 15.0, watchOS is below 8.0, or their Debian/Fedora system runs the vulnerable WebKit packages from the affected distribution versions.

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 8.0 / 12.0.1 / 14.8 or later
Fixed in 8.012.0.114.8
Interim mitigation

Apply the vendor-supplied updates: iOS 14.8/iPadOS 14.8, iOS 15/iPadOS 15, Safari 15, tvOS 15, or watchOS 8 depending on the affected device. Prioritize updating mobile devices and any systems with direct internet exposure.

Recommended fix High confidence

Apple: iOS 14.8+, iPadOS 14.8+, watchOS 8+, tvOS 15+, Safari 15+, macOS 12.0.1+ | Linux: Apply vendor security patches for webkit2gtk

  1. For Apple devices: Upgrade to iOS 14.8, iPadOS 14.8, watchOS 8, tvOS 15, Safari 15, or macOS 12.0.1 (or later) as specified in Apple's security updates
  2. For iOS 15 and iPadOS 15 users: Ensure you are running iOS 15 and iPadOS 15 (the description indicates this version contains the fix)
  3. For Safari users on macOS: Upgrade to Safari 15 or later
  4. For Linux systems (Debian, Fedora): Apply vendor-supplied security patches for the WebKitGTK/webkit2gtk component that addresses this vulnerability
  5. After upgrading, verify the system reports the correct version number to confirm the update was applied
Caveat Major OS version upgrades (e.g., to iOS 15, macOS 12) may include feature changes; review release notes for compatibility concerns with dependent applications

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

Fix this in Safari 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-2021-30846 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

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