Security Resilience

CVE-2021-1789

Memory Safety in Apple Mac Os X 10.14 – 10.14.6

CISA KEVActive ExploitationEUVD ExploitedMemory Safety
Published
02 April 2021
Modified
23 October 2025
KEV Added
04 May 2022
Patch / advisory
View advisory
CVSS Score v3.1 8.8
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
EPSS Score 0.14 96th percentile
Risk Priority 90 floored blend · peak EPSS

CVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.

Summary

CVE-2021-1789 is a high-severity Type Confusion (CWE-843) vulnerability in Apple Mac Os X. Its CVSS base score is 8.8 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Junk Data (T1001.001); ranked in the top 4% of CVEs by exploit likelihood; CISA has added it to the Known Exploited Vulnerabilities catalog.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

A type confusion vulnerability, tracked as CWE-843, was present in WebKit and addressed through improved state handling. The flaw affects multiple Apple platforms prior to the listed updates, including macOS versions before Big Sur 11.2, Catalina, and Mojave, iOS and iPadOS before 14.4, tvOS before 14.4, watchOS before 7.3, and Safari before 14.0.3. The CVSS 3.1 base score of 8.8 reflects network attack vector, low attack complexity, and no required privileges.

An unauthenticated remote attacker can exploit the issue by supplying maliciously crafted web content that a user processes in a vulnerable browser or application. Successful exploitation grants arbitrary code execution with full impact on confidentiality, integrity, and availability of the affected device.

Apple security updates for the affected platforms and Safari 14.0.3 resolve the vulnerability. Related packages were also addressed in distributions such as Fedora and Gentoo that incorporate WebKit components. No information on in-the-wild exploitation is provided in the references.

EU & UK References

Vulnerability Data

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…

more

crafted web content may lead to arbitrary code execution.

CWE(s)
CWE-843
KEV Date Added
04 May 2022

Related Threats

MITRE ATT&CK Enterprise Techniques

T1001.001 Junk Data Command And Control
Adversaries may add junk data to protocols used for command and control to make detection more difficult.
attack.mitre.org →
T1003 OS Credential Dumping Credential Access
Adversaries may attempt to dump credentials to obtain account login and credential material, normally in the form of a hash or a clear text password.
attack.mitre.org →
T1003.005 Cached Domain Credentials Credential Access
Adversaries may attempt to access cached domain credentials used to allow authentication to occur in the event a domain controller is unavailable.
attack.mitre.org →
T1003.006 DCSync Credential Access
Adversaries may attempt to access credentials and other sensitive information by abusing a Windows Domain Controller's application programming interface (API)(Citation: Microsoft DRSR Dec 2017) (Citation: Microsoft GetNCCChanges) (Citati…
attack.mitre.org →
T1005 Data from Local System Collection
Adversaries may search local system sources, such as file systems, configuration files, local databases, virtual machine files, or process memory, to find files of interest and sensitive data prior to Exfiltration.
attack.mitre.org →
T1011.001 Exfiltration Over Bluetooth Exfiltration
Adversaries may attempt to exfiltrate data over Bluetooth rather than the command and control channel.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

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CVE-2023-23529Same product: Apple Ipadosboth on KEV
CVE-2021-1870Same product: Apple Ipadosboth on KEV
CVE-2021-30952Same product: Apple Ipadosboth on KEV
CVE-2023-28204Same product: Apple Ipadosboth on KEV
CVE-2019-8506Same product: Apple Iphone Osboth on KEV

Affected Assets

apple
ipados
≤ 14.4
apple
iphone os
≤ 14.4
apple
mac os x
10.14.6, 10.15.7 · 10.14 — 10.14.6 · 10.15 — 10.15.7
apple
macos
11.0 — 11.2
apple
tvos
≤ 14.4
apple
watchos
≤ 7.3
fedoraproject
fedora
32, 33
webkitgtk
webkitgtk
≤ 2.30.6

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)

—

Validate
Prove the fix (OWASP ASVS)
  • V1.5.2
  • V15.3.5

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 partial match
blocks

Secure SDLC practices directly prevent type-confusion flaws via safe typing, static analysis, and code review while the control itself addresses many additional weaknesses.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.5.14 Information transfer partial match
removes
A.5.15 Access control partial match
removes
A.5.16 Identity management partial match
removes
A.5.17 Authentication information partial match
removes
A.5.18 Access rights partial match
removes
A.8.10 Information deletion partial match
removes

References