Security readout for executives and security teams
Plain-English summary
CVE-2020-9818 is an Apple memory-corruption bug triggered by processing a malicious mail message. Apple fixed it in listed iOS, iPadOS, and watchOS releases. Because CISA lists it as known exploited, exposed mobile devices should be treated as urgent.
Executive priority
Prioritize remediation for executives, administrators, and users handling sensitive email. KEV listing means this is not theoretical, but the provided evidence supports high urgency rather than unbounded assumptions.
Technical view
The issue is a CWE-787 out-of-bounds write in Apple mail-message processing. CVSS 3.1 is 8.8 with network attack vector, low complexity, no privileges, user interaction required, and high confidentiality, integrity, and availability impact.
Likely exposure
Organizations are exposed if they still operate Apple devices below iOS/iPadOS 13.5, iOS 12.4.7 for older devices, or watchOS 6.2.5. The source bundle does not provide exact vulnerable version ranges beyond fixed releases.
Exploitation context
CISA KEV status supports known exploitation. The provided sources do not include exploit mechanics, indicators of compromise, campaign details, or whether exploitation is widespread today.
Researcher notes
Do not infer affected builds beyond the fixed versions named by Apple. Useful next checks are asset version mapping, MDM compliance evidence, and vendor advisory review. The bundle lacks technical root-cause detail and detection indicators.
Mitigation direction
- Update iPhone and iPad devices to iOS/iPadOS 13.5 or later where applicable.
- Update older eligible iOS devices to iOS 12.4.7 or later.
- Update Apple Watch devices to watchOS 6.2.5 or later.
- Check Apple and CISA guidance for any newer vendor instructions.
- Retire or isolate devices unable to run fixed Apple releases.
Validation and detection
- Inventory Apple mobile and watchOS assets through MDM or endpoint management.
- Confirm installed OS versions meet or exceed Apple's fixed releases.
- Flag unmanaged or rarely connected Apple devices for manual verification.
- Review Mail crash telemetry where available; absence of crashes does not prove safety.
- Confirm security update compliance reporting after remediation.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-787: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2020-9818 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 8.8 (3.1)
- Known Exploited
- Yes
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CISA KEV status
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H2.85.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
8.8HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://support.apple.com/HT211168CVE reference · x_refsource_MISC
- https://support.apple.com/HT211175CVE reference · x_refsource_MISC
- https://support.apple.com/HT211169CVE reference · x_refsource_MISC
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2020-9818CVE reference · government-resource
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Out-of-bounds Write
Out-of-bounds Write represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.