Security readout for executives and security teams
Plain-English summary
This Apple vulnerability lets malicious web content trigger arbitrary code execution through an integer overflow. It is important because users can encounter hostile content while browsing, and CISA lists the CVE as known exploited. Apple addressed it with improved input validation in specific iOS, iPadOS, tvOS, Safari, and macOS updates.
Executive priority
Treat this as a high-priority Apple patching issue because it combines arbitrary code execution from malicious web content with CISA known-exploited status.
Technical view
CVE-2021-30663 is a CWE-190 integer overflow in Apple software. The cited Apple text says processing maliciously crafted web content may lead to arbitrary code execution. Fixes are identified in iOS/iPadOS 14.5.1, iOS 12.5.3, tvOS 14.6, Safari 14.1.1, and macOS Big Sur 11.3.1.
Likely exposure
Organizations with Apple endpoints or browsers below the fixed versions may be exposed. The source bundle does not fully enumerate every vulnerable prior version, so confirm affected status against Apple advisories and device inventory.
Exploitation context
CISA KEV status supports that this CVE has been exploited in the wild. The provided sources do not describe exploit mechanics, campaign details, targeting, or indicators, so no further exploitation claims should be assumed.
Researcher notes
The affected data in the bundle is incomplete and repeats macOS entries, but the description names fixed Apple releases. Focus validation on version posture and Apple advisory alignment rather than unsupported assumptions about vulnerable builds.
Mitigation direction
- Update affected Apple devices and Safari to the fixed versions or later.
- Prioritize managed endpoints used for web browsing or external content handling.
- Use MDM or asset tooling to enforce minimum Apple OS and Safari versions.
- Check Apple advisory pages for product-specific remediation details.
Validation and detection
- Inventory macOS, iOS, iPadOS, tvOS, and Safari versions across managed assets.
- Confirm devices meet or exceed Apple’s fixed versions listed for this CVE.
- Review vulnerability scanner or MDM findings for remaining CVE-2021-30663 exposure.
- Track CISA KEV status in remediation reporting and exception workflows.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-190: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2021-30663 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 7.8 (3.1)
- Known Exploited
- Yes
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CISA KEV status
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H1.85.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
7.8HighVector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://support.apple.com/en-us/HT212532CVE reference · x_refsource_MISC
- https://support.apple.com/en-us/HT212534CVE reference · x_refsource_MISC
- https://support.apple.com/en-us/HT212341CVE reference · x_refsource_MISC
- https://support.apple.com/en-us/HT212335CVE reference · x_refsource_MISC
- https://support.apple.com/en-us/HT212336CVE reference · x_refsource_MISC
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-30663CVE reference · government-resource
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Integer Overflow or Wraparound
Integer Overflow or Wraparound represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.