Cyber Resilience

CVE-2020-9818

Memory Safety in Apple Iphone Os ≤ 12.4.7

CISA KEVActive ExploitationEUVD ExploitedMemory Safety
Published
09 June 2020
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 0.023 82th percentile
Risk Priority 90 floored blend · peak EPSS

Summary

CVE-2020-9818 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 18% 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.

An out-of-bounds write vulnerability, tracked as CVE-2020-9818 and assigned CWE-787, affects the mail message processing component in Apple iOS, iPadOS, and watchOS. The flaw stems from insufficient bounds checking when handling crafted input, which can result in unexpected memory modification or application termination. It carries a CVSS 3.1 base score of 8.8 reflecting network attack vector, low complexity, no required privileges, and required user interaction.

An unauthenticated remote attacker can exploit the issue by sending a maliciously crafted email message that the victim processes in the Mail application. Successful exploitation may allow arbitrary memory writes, enabling impacts to confidentiality, integrity, and availability of the affected process without further user action beyond viewing the message.

Apple security advisories for iOS 13.5, iPadOS 13.5, iOS 12.4.7, and watchOS 6.2.5 state that the vulnerability is resolved through improved bounds checking in those releases, with the corresponding updates available via the referenced support documents. No additional mitigation details or workarounds are specified in the provided references.

EU & UK References

Vulnerability Data

An out-of-bounds write issue was addressed with improved bounds checking. This issue is fixed in iOS 13.5 and iPadOS 13.5, iOS 12.4.7, watchOS 6.2.5. Processing a maliciously crafted mail message may lead to unexpected memory modification or application termination.

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-2020-9819Same product: Apple Ipadosboth on KEV
CVE-2022-32894Same product: Apple Ipadosboth on KEV
CVE-2021-30807Same product: Apple Ipadosboth on KEV
CVE-2022-42827Same product: Apple Ipadosboth on KEV
CVE-2022-22675Same product: Apple Ipadosboth on KEV
CVE-2020-27930Same product: Apple Ipadosboth on KEV
CVE-2021-30665Same product: Apple Ipadosboth on KEV
CVE-2021-30883Same product: Apple Ipadosboth on KEV
CVE-2020-3837Same product: Apple Ipadosboth on KEV
CVE-2022-22587Same product: Apple Ipadosboth on KEV

Affected Assets

apple
ipados
≤ 13.5
apple
iphone os
≤ 12.4.7 · 13.0 — 13.5
apple
watchos
≤ 6.2.5

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