CVE Intelligence
CISA KEV High Memory corruption

CVE-2021-1789 — Apple Multiple Products Type Confusion Vulnerability

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 crafted web content may lead to arbitrary code execution.

Published Apr 2, 2021 · Updated Oct 13, 2026 · Sources: CISA Known Exploited Vulnerabilities, CVE Program (cve.org) e CISA ADP, NIST National Vulnerability Database · CNA: apple

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

CISA KEV · May 4, 2022
How the score was calculated
  • Confirmed exploitation (CISA KEV)+35
  • EPSS 14% (30-day exploitation probability)+14
  • Technical severity (high)+6

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation
Confirmed
CISA KEV, listed May 4, 2022
EPSS FIRST
13.98%
ahead of 97% of scored CVEs · Oct 14, 2026
Affects
Apple
iOS and iPadOS and 8 more
CVSS base
8.8
High · 3 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation
Active
none · proof-of-concept · active
Automatable
No
can an attacker script the kill-chain steps
Technical impact
Total
partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

CISA required action CISA

Apply updates per vendor instructions.

US federal deadline: May 25, 2022 — passed 1604 day(s) ago

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

  1. Identify exposed assets running the affected vendor/product/version combinations (Apple iOS and iPadOS, Apple Ipados, Apple Iphone Os…).
  2. Treat as emergency remediation: the CVE is in CISA KEV (confirmed exploitation).
  3. The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
  4. No fix documented in the sources: reduce exposure and monitor the vendor advisory.
  5. Exploitation requires user interaction: tighten email/web filtering and warn affected users.
  6. EPSS ahead of 97% of scored CVEs: prioritize it in the patch queue.
  7. Search available logs for exploit probes matching the vulnerability class (memory corruption), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Apple iOS and iPadOS < 14.4 Vulnerable CVE Program (cve.org) e CISA ADP
Apple Ipados < 14.4 Vulnerable NIST National Vulnerability Database
Apple Iphone Os < 14.4 Vulnerable NIST National Vulnerability Database
Apple Mac Os X version 10.14.6-security_update_2020-006version 10.14.6-security_update_2019-006version 10.14.6-security_update_2019-007version 10.14.6-security_update_2020-001version 10.14.6-security_update_2020-002version 10.14.6-security_update_2020-003version 10.14.6-security_update_2020-004version 10.14.6-security_update_2020-005
and 10 more version 10.14.6version 10.14.6-security_update_2020-007version 10.14.6-supplemental_updateversion 10.14.6-supplemental_update_2version 10.15.7version 10.15.7-supplemental_updateversion 10.14.6-security_update_2019-005version 10.14.6-security_update_2019-004≥ 10.15 and < 10.15.7≥ 10.14 and < 10.14.6
Vulnerable NIST National Vulnerability Database
Apple Macos ≥ 11.0 and < 11.2 Vulnerable NIST National Vulnerability Database
Apple Macos < 14.0< 14.4< 7.3< 11.2 Vulnerable CVE Program (cve.org) e CISA ADP
Apple Tvos < 14.4 Vulnerable NIST National Vulnerability Database
Apple Watchos < 7.3 Vulnerable NIST National Vulnerability Database
Fedoraproject Fedora version 32version 33 Vulnerable NIST National Vulnerability Database
Webkitgtk Webkitgtk < 2.30.6 Vulnerable NIST National Vulnerability Database

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactScored by
8.8 CVSS 3.1 High 2.8 5.9 nvd@nist.gov via NIST National Vulnerability Database
8.8 CVSS 3.1 High 2.8 5.9 134c704f-9b21-4f2e-91b3-4a467353bcc0 via NIST National Vulnerability Database
8.8 CVSS 3.1 High — — CISA-ADP via CVE Program (cve.org) e CISA ADP
6.8 CVSS 2.0 Medium 8.6 6.4 nvd@nist.gov via NIST National Vulnerability Database
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H (score shown at the top: nvd@nist.gov)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-843 · Type Confusion

Other CVEs with this weakness →

CISA KEV details CISA

CISA lists a CVE once it has evidence of exploitation against real targets.

Listed
May 4, 2022
Federal deadline
May 25, 2022
passed 1604 day(s) ago
Ransomware use
Unknown

CISA records ransomware use only for campaigns it has confirmed, so “Unknown” means unrecorded, not ruled out. The deadline binds US federal agencies; for everyone else it is a reference date.

EPSS over time FIRST

Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 13.98%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

  • Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
  • Correlate service crashes/restarts with inbound traffic; repeated crashes may indicate attempts.
  • Hunt retroactively in logs from before May 4, 2022 (KEV listing): exploitation may have started earlier.
web/proxy/WAF logsnetwork IDS/IPSendpoint telemetry (EDR)crash dumps

Timeline

What happened to this CVE, newest first.

  • 2026
  • Affected products added · apple/ipados, apple/iphone os, apple/mac os x, apple/macos, apple/tvos, apple/watchos, fedoraproject/fedora, webkitgtk/w
    Oct 13, 2026 · NIST National Vulnerability Database
  • Source status changed · Published → Analyzed
    Oct 13, 2026 · NIST National Vulnerability Database
  • Record published
    Oct 13, 2026
  • Affected products added · apple/ios and ipados, apple/macos
    Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
  • CVSS changed · 8.8
    Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
  • Source status changed · → Published
    Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
  • SSVC assessment updated
    Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
  • Added to CISA KEV (detected)
    Oct 13, 2026 · CISA Known Exploited Vulnerabilities
  • Record created in this database
    Oct 13, 2026 · CISA Known Exploited Vulnerabilities
  • 2022
  • Added to CISA KEV catalog
    May 3, 2022 · CISA
  • 2021
  • CVE published
    Apr 2, 2021 · apple

Source activity

Repeated readings are counted rather than listed.

  • 2× References added · Oct 13, 2026 – Oct 13, 2026
  • 1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

9 on the record

Elsewhere on this site

Apple
every CVE for this vendor
2022-05
what else CISA listed that month
Memory corruption
same class
CWE-843
other pages naming this weakness

Related CVEs (same products)

  • CVE-2026-86950 Apple Multiple Products Out-of-Bounds Write Vulnerability KEV 17d
  • CVE-2026-86903 Out-of-bounds Read in Apple Ipados Sep 14, 2026
  • CVE-2026-86904 A privacy issue was addressed with improved state management. This issue is fixed in iOS… Sep 14, 2026
  • CVE-2026-86924 Improper Input Validation in Apple Ipados Sep 14, 2026
  • CVE-2026-86905 Improper Access Control in Apple Ipados Sep 14, 2026
  • CVE-2026-86902 Path Traversal in Apple Macos Sep 14, 2026

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No fixed version, patch or mitigation documented.
  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2021-1789 is "Apple Multiple Products Type Confusion Vulnerability", rated High. It affects iOS and iPadOS (Apple); versions are in the scope table. It is in CISA KEV: there is evidence of real-world exploitation. CVSS 8.8 describes technical severity. EPSS 13.98% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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