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CVE Record

CVE-2021-30939: An out-of-bounds read was addressed with improved bounds checking.

An out-of-bounds read was addressed with improved bounds checking. This issue is fixed in macOS Big Sur 11.6.2, tvOS 15.2, macOS Monterey 12.1, Security Update 2021-008 Catalina, iOS 15.2 and iPadOS 15.2, watchOS 8.3. Processing a maliciously crafted image may lead to arbitrary code execution.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

CVE-2021-30939 is an Apple image-processing flaw where a maliciously crafted image could cause arbitrary code execution. Apple fixed it across macOS, iOS/iPadOS, tvOS, and watchOS releases. The public bundle does not provide CVSS, CWE, or evidence of active exploitation.

Executive priority

Treat this as a high-priority Apple patching item because the stated impact is arbitrary code execution from image handling, even though active exploitation is not evidenced here.

Technical view

The issue is described as an out-of-bounds read corrected by improved bounds checking. Impact is arbitrary code execution when a malicious image is processed. Fixed versions include iOS/iPadOS 15.2, watchOS 8.3, tvOS 15.2, macOS Monterey 12.1, macOS Big Sur 11.6.2, and Catalina Security Update 2021-008.

Likely exposure

Organizations are mainly exposed through Apple devices running versions older than the named fixed releases. Exposure is broader where unmanaged or lightly managed endpoints process untrusted image content.

Exploitation context

The source bundle states malicious image processing may lead to arbitrary code execution. It does not include KEV status, public exploitation evidence, exploit maturity, or weaponized details.

Researcher notes

The bundle lacks CVSS, CWE, and detailed component metadata. Talos and ZDI are cited public references, but this analysis relies only on the provided bundle facts: out-of-bounds read, malicious image trigger, Apple fixed releases, and no KEV listing.

Mitigation direction

  • Update affected Apple devices to the fixed OS or security update versions.
  • Prioritize unmanaged, internet-facing, and high-value user devices for update verification.
  • Check Apple advisories for product-specific upgrade guidance and prerequisites.
  • Retire or isolate Apple devices that cannot receive supported security updates.

Validation and detection

  • Inventory Apple device OS versions across MDM and endpoint tools.
  • Confirm iOS and iPadOS devices are at least 15.2 where applicable.
  • Confirm macOS systems have Monterey 12.1, Big Sur 11.6.2, or Catalina 2021-008.
  • Confirm tvOS devices are at least 15.2 and watchOS devices at least 8.3.
  • Track exceptions for devices below fixed versions with owner and remediation date.
Prepared
Confidence
medium
Sources
10

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

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.

description · low confidence lookup

Execution 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.

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cve · low confidence lookup

CVE-2021-30939 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

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.

0CVSS vectors
0Timeline events
0ADP providers
9Source links

CVSS and timeline data

No CVSS vectors or timeline events were available in the normalized CVE source material.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
ApplewatchOSunspecifiedListed
AppleiOS and iPadOSunspecifiedListed
ApplemacOSunspecifiedListed
ApplemacOSunspecifiedListed
ApplemacOSunspecifiedListed
ApplemacOSunspecifiedListed
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.