Security readout for executives and security teams
Plain-English summary
CVE-2021-30661 is an Apple memory-safety flaw triggered by maliciously crafted web content. Successful exploitation could allow arbitrary code execution. Apple reported possible active exploitation and CISA lists it in KEV, so unpatched Apple endpoints should be treated as a real-world risk, not a theoretical issue.
Executive priority
Prioritize remediation for any still-unpatched Apple fleet assets. The combination of arbitrary code execution, web-content trigger, and KEV status makes this a high-priority legacy exposure, especially for unmanaged or unsupported devices.
Technical view
The issue is a use-after-free vulnerability, CWE-416, in Apple web content processing. CVSS 3.1 is 8.8: network reachable, low complexity, no privileges, user interaction required, with high confidentiality, integrity, and availability impact. Apple fixed it with improved memory management in Safari 14.1 and listed OS releases.
Likely exposure
Exposure is most likely on Apple devices or Safari installations below Safari 14.1, iOS 12.5.3, iOS/iPadOS 14.5, watchOS 7.4, tvOS 14.5, or macOS Big Sur 11.3. The source bundle does not provide detailed vulnerable build ranges.
Exploitation context
Apple stated it was aware of a report that the issue may have been actively exploited. CISA KEV inclusion supports treating exploitation as confirmed operational risk. Sources do not provide exploit details, affected campaigns, or indicators of compromise.
Researcher notes
The bundle does not identify the exact component name, exploit chain, or vulnerable version floor. Validation should focus on Apple fixed-version mapping and asset inventory rather than attempting exploit reproduction. Avoid assuming compromise without telemetry or vendor-provided indicators.
Mitigation direction
- Upgrade affected Apple platforms to Apple’s fixed versions or later.
- Prioritize internet-facing and executive-user Apple devices for update verification.
- Check Apple support pages for product-specific security update guidance.
- Restrict use of unsupported Apple OS versions where updates are unavailable.
- Monitor CISA KEV requirements if subject to federal or aligned policy.
Validation and detection
- Inventory Apple devices, OS versions, and Safari versions.
- Confirm versions meet or exceed Apple’s fixed release levels.
- Review patch management records for the relevant April-May 2021 Apple updates.
- Check EDR and web telemetry for suspicious browser or WebKit crashes.
- Document exceptions where devices cannot receive vendor fixes.
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-416: 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-2021-30661 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
- 8.8 (3.1)
- Known Exploited
- Yes
- Published
Vector: CVSS:3.1/AV:N/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:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H2.85.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
8.8HighVector: CVSS:3.1/AV:N/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/HT212317CVE reference · x_refsource_MISC
- https://support.apple.com/en-us/HT212323CVE reference · x_refsource_MISC
- https://support.apple.com/en-us/HT212324CVE reference · x_refsource_MISC
- https://support.apple.com/en-us/HT212325CVE reference · x_refsource_MISC
- https://support.apple.com/en-us/HT212341CVE reference · x_refsource_MISC
- https://support.apple.com/en-us/HT212318CVE reference · x_refsource_MISC
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-30661CVE 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.