Security readout for executives and security teams
Plain-English summary
CVE-2021-1789 is an Apple web content vulnerability that could let malicious web content run code on a user’s device. It is serious because it affects common Apple platforms and Safari-era components, requires only user interaction with crafted content, and is listed by CISA as known exploited.
Executive priority
Treat this as a priority endpoint and browser patching item. Known exploitation and potential arbitrary code execution make delayed remediation risky, especially for executives, administrators, developers, and users handling untrusted web or message content.
Technical view
The issue is a CWE-843 type confusion flaw addressed with improved state handling. Apple states maliciously crafted web content may lead to arbitrary code execution. CVSS 3.1 is 8.8 with network attack vector, low complexity, no privileges required, user interaction required, and high confidentiality, integrity, and availability impact.
Likely exposure
Exposure is most likely on Apple devices or Safari installations older than iOS/iPadOS 14.4, macOS Big Sur 11.2, Safari 14.0.3, tvOS 14.4, watchOS 7.3, or the named Catalina and Mojave security updates. Fedora and Gentoo advisories indicate downstream package exposure should also be checked where relevant.
Exploitation context
CISA KEV status supports that exploitation has been observed. The provided sources do not describe exploit prevalence, current targeting, exploit chains, or whether exploitation remains active today. The attack path requires a user to process maliciously crafted web content.
Researcher notes
Evidence is strongest for Apple advisory fixes and CISA KEV status. The bundle does not include proof-of-concept details, exploit chain context, or precise vulnerable version ranges beyond fixed release names. Validate by product version and vendor advisory mapping, not by assumptions about every WebKit consumer.
Mitigation direction
- Update Apple systems to the fixed versions named in Apple advisories.
- Apply Safari 14.0.3 or later where Safari is separately maintained.
- Apply relevant Fedora or Gentoo security updates if those advisories match deployed packages.
- Prioritize remediation for internet-facing browsing, email, and messaging workflows.
- Check vendor guidance for any unsupported platform-specific options.
Validation and detection
- Inventory Apple OS and Safari versions across managed endpoints.
- Confirm iOS and iPadOS devices are on 14.4 or later.
- Confirm macOS Big Sur is 11.2 or later, or Catalina/Mojave security updates are installed.
- Check Linux package managers against the Fedora and Gentoo advisory packages where applicable.
- Review vulnerability tooling for CVE-2021-1789 detections and stale exceptions.
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-843: 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 lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2021-1789 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/en-us/HT212147CVE reference · x_refsource_MISC
- https://support.apple.com/en-us/HT212146CVE reference · x_refsource_MISC
- https://support.apple.com/en-us/HT212148CVE reference · x_refsource_MISC
- https://support.apple.com/en-us/HT212149CVE reference · x_refsource_MISC
- https://support.apple.com/en-us/HT212152CVE reference · x_refsource_MISC
- FEDORA-2021-864dc37032CVE reference · vendor-advisory, x_refsource_FEDORA
- FEDORA-2021-619711d709CVE reference · vendor-advisory, x_refsource_FEDORA
- GLSA-202104-03CVE reference · vendor-advisory, x_refsource_GENTOO
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-1789CVE 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.