CVE-2021-30762
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 · uneditedA use after free issue was addressed with improved memory management. This issue is fixed in iOS 12.5.4. Processing maliciously crafted web content may lead to arbitrary code execution. Apple is aware of a report that this issue may have been actively exploited..
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 confidenceThis is a use-after-free vulnerability in WebKit (the browser engine used in Safari on iOS) that allows arbitrary code execution when processing maliciously crafted web content. The vulnerability affects iOS versions prior to 12.5.4 and was being actively exploited in the wild as a zero-day, making it a critical priority for organizations with affected devices.
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< 12.5.4CVSS 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
- High
- Availability
- High
CVSS:3.1/AV:N/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 checksWork through these to decide whether this CVE applies to you.
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Check the iOS version on the deviceGo to Settings > General > About > Version on the iOS device, or connect to a computer with iTunes/Finder and check the device summaryAffected if The version displayed is less than 12.5.4 (for example, 12.5.3, 12.5.2, 12.5.1, 12.5.0, or earlier)
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Identify the device model and iOS capabilityCheck the device model in Settings > General > About > Model Name to confirm it can run iOS 12Affected if The device supports iOS 12 but is running a version lower than 12.5.4
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Confirm WebKit-based browser availabilityWebKit is the engine behind Safari on iOS; verify Safari is present and accessible on the device (Settings > Safari)Affected if Safari or any WebKit-based browser is enabled and the iOS version is below 12.5.4
The device is affected if it is running any iOS version prior to 12.5.4 and has Safari or WebKit-based browser functionality accessible.
Generated from the published advisory. Verify against your own configuration.
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 · scoped12.5.4
Immediately update all vulnerable iOS devices to version 12.5.4 or later. For devices that cannot be updated, restrict web browsing capabilities and disable JavaScript in Safari until the update can be applied.
iOS 12.5.4
- Backup your device data using iTunes or iCloud before proceeding
- Connect your device to a computer and open iTunes (or Finder on macOS Catalina and later)
- Check for updates in iTunes/Finder or go to Settings > General > Software Update on the device
- Download and install iOS 12.5.4 or later
- After installation, verify the update by checking Settings > General > About > Version shows 12.5.4 or higher
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation4.0 h
- Implementation8.0 h
- Testing4.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $5,120.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-30762 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-30762 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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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.
- 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