Cyber 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 0.13 96th percentile
Risk Priority 90 floored blend · peak EPSS

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 Exploitation for Privilege Escalation (T1068); 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

T1068 Exploitation for Privilege Escalation Privilege Escalation
Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.
attack.mitre.org →
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
T1203 Exploitation for Client Execution Execution
Adversaries may exploit software vulnerabilities in client applications to execute code.
attack.mitre.org →
T1210 Exploitation of Remote Services Lateral Movement
Adversaries may exploit remote services to gain unauthorized access to internal systems once inside of a network.
attack.mitre.org →
T1212 Exploitation for Credential Access Credential Access
Adversaries may exploit software vulnerabilities in an attempt to collect credentials.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2023-32439Same product: Apple Ipadosboth on KEV
CVE-2020-27932Same product: Apple Ipadosboth on KEV
CVE-2021-30869Same product: Apple Ipadosboth on KEV
CVE-2022-42856Same product: Apple Ipadosboth on KEV
CVE-2024-23222Same product: Apple Ipadosboth on KEV
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
  • V3.2.3
  • 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 mostly match
prevents

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.8.29 Security testing in development and acceptance mostly match
finds

Security testing in development can detect type-confusion vulnerabilities through fuzzing and static analysis.

A.8.25 Secure development life cycle partial match
prevents

Secure SDLC mandates type-safe design and review that can catch type-confusion flaws.

A.8.26 Application security requirements partial match
prevents

Application security requirements can specify strong typing and interface contracts that reduce type confusion.

A.8.27 Secure system architecture and engineering principles partial match
prevents

Secure architecture principles promote type-safe languages and memory-safety mechanisms that mitigate type confusion.

A.8.28 Secure coding partial match
prevents

Secure coding standards directly forbid unsafe type casts and require static-analysis checks for type confusion.

References