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Vulnerabilities/CVE-2021-1789Public Intelligence Dossier
Source: apple · Limited verification•Last verified: •Collection Degraded
CVE-2021-1789ListedHIGH (raw)CVSS 8.8CWE-843

A type confusion issue was addressed with improved state handling

Published: 02 Apr 2021•Last updated: 17 Jun 2026, 09:02 AM IST•Source identifier: product-security@apple.com
Dossier completeness: source-provided sections 3 / 3 · rule guidance available. Missing source facts count as incomplete.
Official source
CISA KEV catalog
Listed
Added04 May 2022
Due25 May 2022
RansomwareUnknown
CVSS score
8.8HIGH (raw)
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Metric sourcenvd@nist.gov
EPSS probability
14%0.140
Percentile97th
Weakness type
CWE-843
No further CWE recorded
Remediation
Patch status unknown
No fixed version or KB recorded

Why It Matters

Analysis dossier

Why It Matters

A type confusion issue was addressed with improved state handling. This issue is fixed in macOS Big Sur 11.2, Security Update 2021-001 Catalina, Security Update 2021-001 Mojave, tvOS 14.4, watchOS 7.3, iOS 14.4 and iPadOS 14.4, Safari 14.0.3. Processing maliciously crafted web content may lead to arbitrary code execution.

SOC priority

Immediate Attention

Actively exploited (source statement)

Yes

Publicly disclosed

Unknown

Risk basis: CISA KEV exploitation signal; HIGH severity; Source-confirmed exploitation or CISA KEV/ransomware metadata

Affected Products & Remediation

8 source-backed products
Affected products and versions (source)
  • apple ipados · < 14.4 · NVD CPE · Source
  • apple iphone os · < 14.4 · NVD CPE · Source
  • apple mac os x · >= 10.14 < 10.14.6; >= 10.15 < 10.15.7; 10.14.6; 10.15.7 · NVD CPE · Source
  • apple macos · >= 11.0 < 11.2 · NVD CPE · Source
  • apple tvos · < 14.4 · NVD CPE · Source
  • apple watchos · < 7.3 · NVD CPE · Source
  • fedoraproject fedora · 32; 33 · NVD CPE · Source
  • webkitgtk webkitgtk · < 2.30.6 · NVD CPE · Source
Recorded patch / KBNot provided by source

Vendor or catalog guidance (source)

  • CISA KEV: Apply updates per vendor instructions.

Known exploitation (source facts)

Only what a source states. Unknown means no source has said either way; it is not "not exploited".

CISA KEV
Listed
Exploited (source statement)
Yes
Publicly disclosed (source)
Unknown

CISA required action: Apply updates per vendor instructions.

Suggested hunting (rule-based inference)

SecOps Signal recommendation (rule-based inference). These steps are hunting hypotheses from the vulnerability class; they do not state or imply that exploitation occurred here or anywhere.

Matched kev-network-exposure (CVSS AV:N, CISA KEV Listed); user-interaction-client (CVSS AV:N, CVSS UI:R)

Exposure

  1. Identify assets with the exact CVE and confirm the affected product/version against the advisory.Telemetry: DeviceTvmSoftwareVulnerabilities · KEV listing raises urgency, but inventory is needed to establish local exposure. · Rule kev-network-exposure
  2. Identify endpoints reporting this CVE, especially those used for email and web browsing.Telemetry: DeviceTvmSoftwareVulnerabilities · A network vector that needs user interaction points at user-facing client software. · Rule user-interaction-client

Exploitation evidence

  1. Review relevant edge or application access logs for unusual requests around the advisory window.Telemetry: CommonSecurityLog · Log review is a hunting hypothesis; KEV listing alone does not show local exploitation. · Rule kev-network-exposure
Show more (2)

Exploitation evidence

  1. Review unusual child processes started by the affected client application on affected endpoints.Telemetry: DeviceProcessEvents · Hunting hypothesis from the CVSS vector; it does not show that exploitation occurred. · Rule user-interaction-client

Response

  1. Recheck the affected assets after the source-stated mitigation or update is applied.Telemetry: DeviceTvmSoftwareVulnerabilities · A follow-up inventory check verifies local remediation. · Rule kev-network-exposure

CISA KEV Record

Catalog entry
04 May 2022
Required action due
25 May 2022
Known ransomware use
Unknown

Apply updates per vendor instructions.

Change History & Source Data

— No recorded material change

CNA / source
product-security@apple.com
Record status · verification
UPDATED · CISA KEV confirmed
CPE
cpe:2.3:o:apple:ipados:*:*:*:*:*:*:*:*, cpe:2.3:o:apple:iphone_os:*:*:*:*:*:*:*:*, cpe:2.3:o:apple:mac_os_x:*:*:*:*:*:*:*:*, cpe:2.3:o:apple:mac_os_x:10.14.6:-:*:*:*:*:*:*, cpe:2.3:o:apple:mac_os_x:10.14.6:security_update_2019-004:*:*:*:*:*:*, cpe:2.3:o:apple:mac_os_x:10.14.6:security_update_2019-005:*:*:*:*:*:*, cpe:2.3:o:apple:mac_os_x:10.14.6:security_update_2019-006:*:*:*:*:*:*, cpe:2.3:o:apple:mac_os_x:10.14.6:security_update_2019-007:*:*:*:*:*:*, cpe:2.3:o:apple:mac_os_x:10.14.6:security_update_2020-001:*:*:*:*:*:*, cpe:2.3:o:apple:mac_os_x:10.14.6:security_update_2020-002:*:*:*:*:*:*

Evidence & Provenance

4 public sources
CISA KEV CatalogAdded 2022-05-04support.apple.comSource recordnvd.nist.govSource recordlists.fedoraproject.orgSource record

Linked by the query's stored exact CVE association. Review required tables and validation status before use.

Detection Hunting Query
Target: DeviceTvmSoftwareVulnerabilities•Defender XDR
Detect endpoints exposed to CVE-2021-1789
Purpose: Exposure assessment (Category: Exposure Check)Why linked: Query metadata names CVE-2021-1789
DeviceTvmSoftwareVulnerabilities| where CveId == "CVE-2021-1789"| project DeviceId, DeviceName, OSPlatform, OSVersion, SoftwareVendor, SoftwareName, SoftwareVersion, CveId, VulnerabilitySeverityLevel, RecommendedSecurityUpdate, RecommendedSecurityUpdateId| sort by VulnerabilitySeverityLevel desc
Schema Checked · Not runtime validatedSource: SecOps Signal deterministic template · Limited verificationStatic screening: Passed structure and schema checks; tenant execution is not verified.
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Correlated briefings

SecOps Signal surfaces public advisory facts only. A missing value means the source has not published it, not that your environment is unaffected. No tenant inventory is connected.