Cyber Resilience

CVE-2021-30665

Memory Safety in Apple Iphone Os ≤ 12.5.3

CISA KEVActive ExploitationEUVD ExploitedMemory Safety
Published
08 September 2021
Modified
23 October 2025
KEV Added
03 November 2021
Patch / 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 0.037 89th percentile
Risk Priority 90 floored blend · peak EPSS

Summary

CVE-2021-30665 is a high-severity Out-of-bounds Write (CWE-787) vulnerability in Apple Iphone Os. 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 11% 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 memory corruption vulnerability, identified as CWE-787, affects multiple Apple platforms and stems from improper state management during the processing of web content. Impacted software includes watchOS prior to 7.4.1, iOS and iPadOS prior to 14.5.1, tvOS prior to 14.6, iOS 12.x prior to 12.5.3, and macOS Big Sur prior to 11.3.1. The flaw carries a CVSS score of 8.8 and enables out-of-bounds write operations when handling untrusted input.

An unauthenticated remote attacker can exploit the issue by supplying maliciously crafted web content that a user is tricked into processing, such as through a web browser or other web-rendering component. Successful exploitation grants arbitrary code execution with full read, write, and execution impact on the affected device.

Apple security advisories for the listed updates state that the vulnerability is resolved by applying the respective patches, which improve state management to prevent the memory corruption. The references detail the fixed versions for each platform and urge immediate installation to address the exposure.

Apple has noted reports indicating that this vulnerability may have been actively exploited in the wild prior to patching.

EU & UK References

Vulnerability Data

A memory corruption issue was addressed with improved state management. This issue is fixed in watchOS 7.4.1, iOS 14.5.1 and iPadOS 14.5.1, tvOS 14.6, iOS 12.5.3, macOS Big Sur 11.3.1. Processing maliciously crafted web content may lead to arbitrary code…

more

execution. Apple is aware of a report that this issue may have been actively exploited..

CWE(s)
KEV Date Added
03 November 2021

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.
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.
T1203 Exploitation for Client Execution Execution
Adversaries may exploit software vulnerabilities in client applications to execute code.
T1210 Exploitation of Remote Services Lateral Movement
Adversaries may exploit remote services to gain unauthorized access to internal systems once inside of a network.
T1211 Exploitation for Stealth Stealth
Adversaries may exploit vulnerabilities to evade detection by hiding activity, suppressing logging, or operating within trusted or unmonitored components.
T1212 Exploitation for Credential Access Credential Access
Adversaries may exploit software vulnerabilities in an attempt to collect credentials.
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2022-22675Same product: Apple Ipadosboth on KEV
CVE-2021-30883Same product: Apple Ipadosboth on KEV
CVE-2024-23225Same product: Apple Ipadosboth on KEV
CVE-2024-23296Same product: Apple Ipadosboth on KEV
CVE-2022-32894Same product: Apple Ipadosboth on KEV
CVE-2021-30807Same product: Apple Ipadosboth on KEV
CVE-2020-27930Same product: Apple Ipadosboth on KEV
CVE-2020-3837Same product: Apple Ipadosboth on KEV
CVE-2022-22587Same product: Apple Ipadosboth on KEV
CVE-2023-28206Same product: Apple Ipadosboth on KEV

Affected Assets

apple
ipados
≤ 14.5.1
apple
iphone os
≤ 12.5.3 · 13.0 — 14.5.1
apple
macos
≤ 11.3.1
apple
tvos
≤ 14.6
apple
watchos
≤ 7.4.1

Mitigating Controls

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

addresses: CWE-787

Out-of-bounds writes that corrupt control flow or inject shellcode are rendered non-executable by the same memory protections.

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-development practices (static analysis, bounds checking, code review) are the primary means of preventing out-of-bounds writes.

ID.RA-01 partial match
prevents

Vulnerability scanning and recording can discover out-of-bounds write flaws so they can be remediated.

PR.PS-02 partial match
prevents

Patching or replacing vulnerable software directly eliminates known instances of this coding weakness.

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.

finds

Security testing in development and acceptance can detect and prevent out-of-bounds write defects.

prevents

Secure development life cycle mandates practices that prevent out-of-bounds writes.

prevents

Application security requirements can specify bounds-checking and safe memory handling.

prevents

Secure architecture and engineering principles reduce the likelihood of buffer overflows.

prevents

Secure coding directly addresses out-of-bounds writes through language choice and coding standards.

prevents

Change management can enforce review gates that catch unsafe memory operations before deployment.

References